Alternative  Primary  Alternative  Primary  Alternative  Primary 
<%  {  and  &&  and_eq  &= 
%>  }  bitor    or_eq  = 
<:  [  or    xor_eq  ^= 
:>  ]  xor  ^  not  ! 
%:  #  compl  ~  not_eq  != 
%:%:  ##  bitand  & 
00A8  00AA  00AD  00AF  00B200B5 
00B700BA  00BC00BE  00C000D6  00D800F6  00F800FF 
0100167F  1681180D  180F1FFF  
200B200D  202A202E  203F2040  2054  2060206F 
2070218F  246024FF  27762793  2C002DFF  2E802FFF 
30043007  3021302F  3031D7FF  
F900FD3D  FD40FDCF  FDF0FE44  FE47FFFD  
100001FFFD  200002FFFD  300003FFFD  400004FFFD  500005FFFD 
600006FFFD  700007FFFD  800008FFFD  900009FFFD  A0000AFFFD 
B0000BFFFD  C0000CFFFD  D0000DFFFD  E0000EFFFD 
0300036F  1DC01DFF  20D020FF  FE20FE2F 
alignas  const_cast  for  public  thread_local 
alignof  continue  friend  register  throw 
asm  decltype  goto  reinterpret_cast  true 
auto  default  if  requires  try 
bool  delete  inline  return  typedef 
break  do  int  short  typeid 
case  double  long  signed  typename 
catch  dynamic_cast  mutable  sizeof  union 
char  else  namespace  static  unsigned 
char16_t  enum  new  static_assert  using 
char32_t  explicit  noexcept  static_cast  virtual 
class  export  nullptr  struct  void 
concept  extern  operator  switch  volatile 
const  false  private  template  wchar_t 
constexpr  float  protected  this  while 
Suffix  Decimal literal  Binary, octal, or hexadecimal literal 
none  int  int 
long int  unsigned int  
long long int  long int  
unsigned long int  
long long int  
unsigned long long int  
u or U  unsigned int  unsigned int 
unsigned long int  unsigned long int  
unsigned long long int  unsigned long long int  
l or L  long int  long int 
long long int  unsigned long int  
long long int  
unsigned long long int  
Both u or U  unsigned long int  unsigned long int 
and l or L  unsigned long long int  unsigned long long int 
ll or LL  long long int  long long int 
unsigned long long int  
Both u or U  unsigned long long int  unsigned long long int 
and ll or LL 
newline  NL(LF)  \n 
horizontal tab  HT  \t 
vertical tab  VT  \v 
backspace  BS  \b 
carriage return  CR  \r 
form feed  FF  \f 
alert  BEL  \a 
backslash  \  \\ 
question mark  ?  \? 
single quote  '  \' 
double quote  "  \" 
octal number  ooo  \ooo 
hex number  hhh  \xhhh 
Source  Means  Source  Means  Source  Means  
u"a"  u"b"  u"ab"  U"a"  U"b"  U"ab"  L"a"  L"b"  L"ab" 
u"a"  "b"  u"ab"  U"a"  "b"  U"ab"  L"a"  "b"  L"ab" 
"a"  u"b"  u"ab"  "a"  U"b"  U"ab"  "a"  L"b"  L"ab" 
no cvqualifier  <  const 
no cvqualifier  <  volatile 
no cvqualifier  <  const volatile 
const  <  const volatile 
volatile  <  const volatile 
Specifier(s)  Type 
typename  the type named 
simpletemplateid  the type as defined in [temp.names] 
templatename  placeholder for a type to be deduced 
char  “char” 
unsigned char  “unsigned char” 
signed char  “signed char” 
char16_t  “char16_t” 
char32_t  “char32_t” 
bool  “bool” 
unsigned  “unsigned int” 
unsigned int  “unsigned int” 
signed  “int” 
signed int  “int” 
int  “int” 
unsigned short int  “unsigned short int” 
unsigned short  “unsigned short int” 
unsigned long int  “unsigned long int” 
unsigned long  “unsigned long int” 
unsigned long long int  “unsigned long long int” 
unsigned long long  “unsigned long long int” 
signed long int  “long int” 
signed long  “long int” 
signed long long int  “long long int” 
signed long long  “long long int” 
long long int  “long long int” 
long long  “long long int” 
long int  “long int” 
long  “long int” 
signed short int  “short int” 
signed short  “short int” 
short int  “short int” 
short  “short int” 
wchar_t  “wchar_t” 
float  “float” 
double  “double” 
long double  “long double” 
void  “void” 
auto  placeholder for a type to be deduced 
decltype(auto)  placeholder for a type to be deduced 
decltype(expression)  the type as defined below 
Subclause  Expression  As member function  As nonmember function 
@a  (a).operator@ ( )  operator@(a)  
a@b  (a).operator@ (b)  operator@(a, b)  
a=b  (a).operator= (b)  
a[b]  (a).operator[](b)  
a>  (a).operator>( )  
a@  (a).operator@ (0)  operator@(a, 0) 
Conversion  Category  Rank  Subclause 
No conversions required  Identity  
Lvaluetorvalue conversion  
Arraytopointer conversion  Lvalue Transformation  
Functiontopointer conversion  Exact Match  
Qualification conversions  
Function pointer conversion  Qualification Adjustment  
Integral promotions  
Floatingpoint promotion  Promotion  Promotion  
Integral conversions  
Floatingpoint conversions  
Floatingintegral conversions  
Pointer conversions  Conversion  Conversion  
Pointertomember conversions  
Boolean conversions 
Operator  Value when parameter pack is empty 
&&  true 
  false 
,  void() 
Clause  Category  
Language support library  
Diagnostics library  
General utilities library  
Strings library  
Localization library  
Containers library  
Iterators library  
Algorithms library  
Numerics library  
Input/output library  
Regular expressions library  
Atomic operations library  
Thread support library 
<algorithm>  <functional>  <new>  <string_view> 
<any>  <future>  <numeric>  <strstream> 
<array>  <initializer_list>  <optional>  <system_error> 
<atomic>  <iomanip>  <ostream>  <thread> 
<bitset>  <ios>  <queue>  <tuple> 
<charconv>  <iosfwd>  <random>  <type_traits> 
<chrono>  <iostream>  <ratio>  <typeindex> 
<codecvt>  <istream>  <regex>  <typeinfo> 
<complex>  <iterator>  <scoped_allocator>  <unordered_map> 
<condition_variable>  <limits>  <set>  <unordered_set> 
<deque>  <list>  <shared_mutex>  <utility> 
<exception>  <locale>  <sstream>  <valarray> 
<execution>  <map>  <stack>  <variant> 
<filesystem>  <memory>  <stdexcept>  <vector> 
<forward_list>  <memory_resource>  <streambuf>  
<fstream>  <mutex>  <string> 
<cassert>  <cinttypes>  <csignal>  <cstdio>  <cwchar> 
<ccomplex>  <ciso646>  <cstdalign>  <cstdlib>  <cwctype> 
<cctype>  <climits>  <cstdarg>  <cstring>  
<cerrno>  <clocale>  <cstdbool>  <ctgmath>  
<cfenv>  <cmath>  <cstddef>  <ctime>  
<cfloat>  <csetjmp>  <cstdint>  <cuchar> 
abort_handler_s  mbstowcs_s  strncat_s  vswscanf_s 
asctime_s  memcpy_s  strncpy_s  vwprintf_s 
bsearch_s  memmove_s  strtok_s  vwscanf_s 
constraint_handler_t  memset_s  swprintf_s  wcrtomb_s 
ctime_s  printf_s  swscanf_s  wcscat_s 
errno_t  qsort_s  tmpfile_s  wcscpy_s 
fopen_s  RSIZE_MAX  TMP_MAX_S  wcsncat_s 
fprintf_s  rsize_t  tmpnam_s  wcsncpy_s 
freopen_s  scanf_s  vfprintf_s  wcsnlen_s 
fscanf_s  set_constraint_handler_s  vfscanf_s  wcsrtombs_s 
fwprintf_s  snprintf_s  vfwprintf_s  wcstok_s 
fwscanf_s  snwprintf_s  vfwscanf_s  wcstombs_s 
getenv_s  sprintf_s  vprintf_s  wctomb_s 
gets_s  sscanf_s  vscanf_s  wmemcpy_s 
gmtime_s  strcat_s  vsnprintf_s  wmemmove_s 
ignore_handler_s  strcpy_s  vsnwprintf_s  wprintf_s 
L_tmpnam_s  strerror_s  vsprintf_s  wscanf_s 
localtime_s  strerrorlen_s  vsscanf_s  
mbsrtowcs_s  strlen_s  vswprintf_s 
Subclause  Header(s)  
<ciso646>  
Types  <cstddef>  
Implementation properties  <cfloat> <limits> <climits>  
Integer types  <cstdint>  
Start and termination  <cstdlib>  
Dynamic memory management  <new>  
Type identification  <typeinfo>  
Exception handling  <exception>  
Initializer lists  <initializer_list>  
Other runtime support  <cstdarg>  
Type traits  <type_traits>  
Atomics  <atomic>  
Deprecated headers  <cstdalign> <cstdbool> 
Expression  Postcondition 
T t;  object t is defaultinitialized 
T u{};  object u is valueinitialized or aggregateinitialized 
T() T{}  an object of type T is valueinitialized
or aggregateinitialized 
Expression  Postcondition 
T u = rv;  u is equivalent to the value of rv before the construction 
T(rv)  T(rv) is equivalent to the value of rv before the construction 
Expression  Postcondition 
T u = v;  the value of v is unchanged and is equivalent to u 
T(v)  the value of v is unchanged and is equivalent to T(v) 
Expression  Return type  Return value  Postcondition 
t = rv  T&  t  If t and rv do not refer to the same object,
t is equivalent to the value of rv before the assignment 
rv's state is unspecified. 
Expression  Return type  Return value  Postcondition 
t = v  T&  t  t is equivalent to v, the value of v is unchanged 
Expression  Postcondition 
u.~T()  All resources owned by u are reclaimed, no exception is propagated. 
Expression  Return type  Operational semantics 
P u(np);  Postconditions: u == nullptr  
P u = np;  
P(np)  Postconditions: P(np) == nullptr  
t = np  P&  Postconditions: t == nullptr 
a != b  contextually convertible to bool  !(a == b) 
a == np  contextually convertible to bool  a == P() 
np == a  
a != np  contextually convertible to bool  !(a == np) 
np != a 
Expression  Return type  Requirement 
h(k)  size_t  The value returned shall depend only on the argument k for the duration of
the program. 
h(u)  size_t  Shall not modify u. 
Variable  Definition 
T, U, C  any cvunqualified object type ([basic.types]) 
X  an Allocator class for type T 
Y  the corresponding Allocator class for type U 
XX  the type allocator_traits<X> 
YY  the type allocator_traits<Y> 
a, a1, a2  lvalues of type X 
u  the name of a variable being declared 
b  a value of type Y 
c  a pointer of type C* through which indirection is valid 
p  a value of type XX::pointer, obtained
by calling a1.allocate, where a1 == a 
q  
w  a value of type XX::void_pointer obtained by
conversion from a value p 
x  a value of type XX::const_void_pointer obtained by
conversion from a value q or a value w 
y  a value of type XX::const_void_pointer obtained by
conversion from a result value of YY::allocate, or else a value of
type (possibly const) std::nullptr_t. 
n  a value of type XX::size_type. 
Args  a template parameter pack 
args  a function parameter pack with the pattern Args&& 
Expression  Return type  Assertion/note  Default 
pre/postcondition  
X::pointer  T*  
X::const_pointer  X::pointer is convertible to X::const_pointer  pointer_traits<X::pointer>::rebind<const T>  
X::void_pointer Y::void_pointer  pointer_traits<X::pointer>::rebind<void>  
X::const_void_pointer Y::const_void_pointer  X::pointer, X::const_pointer, and X::void_pointer are convertible to X::const_void_pointer.  pointer_traits<X::pointer>::rebind<const void>  
X::value_type  Identical to T  
X::size_type  unsigned integer type  a type that can represent the size of the largest object in the allocation model.  make_unsigned_t<X::difference_type> 
X::difference_type  signed integer type  a type that can represent the difference between any two pointers
in the allocation model.  pointer_traits<X::pointer>::difference_type 
typename X::template rebind<U>::other  Y  See Note A, below.  
*p  T&  
*q  const T&  *q refers to the same object as *p  
p>m  type of T::m  equivalent to (*p).m  
q>m  type of T::m  equivalent to (*q).m  
static_cast<X::pointer>(w)  X::pointer  static_cast<X::pointer>(w) == p  
static_cast<X::const_pointer>(x)  X::const_pointer  static_cast< X::const_pointer>(x) == q  
pointer_traits<X::pointer>::pointer_to(r)  X::pointer  
a.allocate(n)  X::pointer  
a.allocate(n, y)  X::pointer  Same as a.allocate(n). The use of y is unspecified, but
it is intended as an aid to locality.  a.allocate(n) 
a.deallocate(p,n)  (not used)  Requires: p shall be a value returned by an earlier call
to allocate that has not been invalidated by
an intervening call to deallocate.  
a.max_size()  X::size_type  the largest value that can meaningfully be passed to X::allocate()  numeric_limits<size_type>::max() / sizeof(value_type) 
a1 == a2  bool  returns true only if storage allocated from each can
be deallocated via the other. operator== shall be reflexive, symmetric,
and transitive, and shall not exit via an exception.  
a1 != a2  bool  same as !(a1 == a2)  
a == b  bool  same as a == Y::rebind<T>::other(b)  
a != b  bool  same as !(a == b)  
X u(a); X u = a;  Shall not exit via an exception. Postconditions: u == a  
X u(b);  Shall not exit via an exception. Postconditions: Y(u) == b, u == X(b)  
X u(std::move(a)); X u = std::move(a);  Shall not exit via an exception.  
X u(std::move(b));  Shall not exit via an exception.  
a.construct(c, args)  (not used)  Effects: Constructs an object of type C at
c  ::new ((void*)c) C(forward<Args>(args)...) 
a.destroy(c)  (not used)  Effects: Destroys the object at c  c>~C() 
a.select_on_container_copy_construction()  X  Typically returns either a or X()  return a; 
X::propagate_on_container_copy_assignment  Identical to or derived from true_type or false_type  true_type only if an allocator of type X should be copied
when the client container is copyassigned. See Note B, below.  false_type 
X::propagate_on_container_move_assignment  Identical to or derived from true_type or false_type  true_type only if an allocator of type X should be moved
when the client container is moveassigned. See Note B, below.  false_type 
X::propagate_on_ container_swap  Identical to or derived from true_type or false_type  See Note B, below.  false_type 
X::is_always_equal  Identical to or derived from true_type or false_type  true_type only if the expression a1 == a2 is guaranteed
to be true for any two (possibly const) values
a1, a2 of type X.  is_empty<X>::type 
Subclause  Header(s)  
Common definitions  <cstddef>  
<cstdlib>  
Implementation properties  <limits>  
<climits>  
<cfloat>  
Integer types  <cstdint>  
Start and termination  <cstdlib>  
Dynamic memory management  <new>  
Type identification  <typeinfo>  
Exception handling  <exception>  
Initializer lists  <initializer_list>  
Other runtime support  <csignal>  
<csetjmp>  
<cstdarg>  
<cstdlib> 
Subclause  Header(s)  
Exception classes  <stdexcept>  
Assertions  <cassert>  
Error numbers  <cerrno>  
System error support  <system_error> 
Subclause  Header(s)  
Utility components  <utility>  
Compiletime integer sequences  <utility>  
Pairs  <utility>  
Tuples  <tuple>  
Optional objects  <optional>  
Variants  <variant>  
Storage for any type  <any>  
Fixedsize sequences of bits  <bitset>  
Memory  <memory>  
<cstdlib>  
Smart pointers  <memory>  
Memory resources  <memory_resource>  
Scoped allocators  <scoped_allocator>  
Function objects  <functional>  
Type traits  <type_traits>  
Compiletime rational arithmetic  <ratio>  
Time utilities  <chrono>  
<ctime>  
Type indexes  <typeindex>  
Execution policies  <execution> 
*this contains a value  *this does not contain a value  
rhs contains a value  assigns *rhs to the contained value  initializes the contained value as if directnonlistinitializing an object of type T with *rhs 
rhs does not contain a value  destroys the contained value by calling val>T::~T()  no effect 
*this contains a value  *this does not contain a value  
rhs contains a value  assigns std::move(*rhs) to the contained value  initializes the contained value as if directnonlistinitializing an object of type T with std::move(*rhs) 
rhs does not contain a value  destroys the contained value by calling val>T::~T()  no effect 
*this contains a value  *this does not contain a value  
rhs contains a value  assigns *rhs to the contained value  initializes the contained value as if directnonlistinitializing
an object of type T with *rhs 
rhs does not contain a value  destroys the contained value by calling val>T::~T()  no effect 
*this contains a value  *this does not contain a value  
rhs contains a value  assigns std::move(*rhs) to the contained value  initializes the contained value as if directnonlistinitializing
an object of type T with std::move(*rhs) 
rhs does not contain a value  destroys the contained value by calling val>T::~T()  no effect 
*this contains a value  *this does not contain a value  
rhs contains a value  calls swap(*(*this), *rhs)  initializes the contained value of *this as if
directnonlistinitializing an object of type T with the expression std::move(*rhs),
followed by rhs.val>T::~T();
postcondition is that *this contains a value and rhs does not contain a value 
rhs does not contain a value  initializes the contained value of rhs as if
directnonlistinitializing an object of type T with the expression std::move(*(*this)),
followed by val>T::~T();
postcondition is that *this does not contain a value and rhs contains a value  no effect 
Template  Condition  Comments 
template <class T> struct is_void;  T is void  
template <class T> struct is_null_pointer;  
template <class T> struct is_integral;  T is an integral type  
template <class T> struct is_floating_point;  T is a floatingpoint type  
template <class T> struct is_array;  T is an array type ([basic.compound]) of known or unknown extent  
template <class T> struct is_pointer;  T is a pointer type  Includes pointers to functions
but not pointers to nonstatic members. 
template <class T> struct is_lvalue_reference;  T is an lvalue reference type  
template <class T> struct is_rvalue_reference;  T is an rvalue reference type  
template <class T> struct is_member_object_pointer;  T is a pointer to data member  
T is a pointer to member function  
T is an enumeration type ([basic.compound])  
template <class T> struct is_union;  T is a union type ([basic.compound])  
template <class T> struct is_class;  T is a nonunion class type ([basic.compound])  
template <class T> struct is_function;  T is a function type ([basic.compound]) 
Template  Condition  Comments 
template <class T> struct is_reference;  T is an lvalue reference or an rvalue reference  
template <class T> struct is_arithmetic;  T is an arithmetic type  
template <class T> struct is_fundamental;  T is a fundamental type  
template <class T> struct is_object;  T is an object type  
template <class T> struct is_scalar;  T is a scalar type  
template <class T> struct is_compound;  T is a compound type  
template <class T> struct is_member_pointer;  T is a pointertomember type ([basic.compound]) 
Template  Condition  Preconditions 
template <class T> struct is_const;  T is constqualified  
template <class T> struct is_volatile;  T is volatilequalified  
template <class T> struct is_trivial;  T is a trivial type  
template <class T> struct is_trivially_copyable;  T is a trivially copyable type  
template <class T> struct is_standard_layout;  T is a standardlayout type  
template <class T> struct is_pod;  T is a POD type  
T is a class type, but not a union type, with no nonstatic data
members other than bitfields of length 0, no virtual member functions,
no virtual base classes, and no base class B for
which is_empty_v<B> is false.  
template <class T> struct is_polymorphic;  T is a polymorphic class  
template <class T> struct is_abstract;  T is an abstract class  
template <class T> struct is_final;  
template <class T> struct is_aggregate;  T is an aggregate type ([dcl.init.aggr])  
If is_arithmetic_v<T> is true, the same result as
T(1) < T(0);
otherwise, false  
template <class T> struct is_unsigned;  If is_arithmetic_v<T> is true, the same result as
T(0) < T(1);
otherwise, false  
template <class T, class... Args> struct is_constructible;  For a function type T or
for a cv void type T,
is_constructible_v<T, Args...> is false,
otherwise see below  T and all types in the parameter pack Args
shall be complete types, cv void,
or arrays of unknown bound. 
template <class T> struct is_default_constructible;  
template <class T> struct is_copy_constructible;  
template <class T> struct is_move_constructible;  
template <class T, class U> struct is_assignable;  Only the validity of the immediate context
of the assignment expression is considered. [ Note : ]The compilation of the
expression can result in side effects such as the instantiation of class template
specializations and function template specializations, the generation of
implicitlydefined functions, and so on. Such side effects are not in the “immediate
context” and can result in the program being illformed. — end note  
template <class T> struct is_copy_assignable;  
template <class T> struct is_move_assignable;  
template <class T, class U> struct is_swappable_with;  The expressions swap(declval<T>(), declval<U>()) and
swap(declval<U>(), declval<T>()) are each wellformed
when treated as an unevaluated operand
in an overloadresolution context
for swappable values ([swappable.requirements]). Only the validity of the immediate context
of the swap expressions is considered. [ Note : ]The compilation of the expressions can result in side effects
such as the instantiation of class template specializations and
function template specializations,
the generation of implicitlydefined functions, and so on. Such side effects are not in the “immediate context” and
can result in the program being illformed. — end note  
template <class T> struct is_swappable;  
template <class T> struct is_destructible;  Either T is a reference type,
or T is a complete object type
for which the expression
declval<U&>().~U()
is wellformed
when treated as an unevaluated operand,
where U is
remove_all_extents_t<T>.  
template <class T, class... Args> struct is_trivially_constructible;  is_constructible_v<T, Args...> is true and the variable definition for is_constructible, as defined below, is known to call no operation that is not trivial ([basic.types], [special]).  T and all types in the parameter pack Args shall be complete types,
cv void, or arrays of unknown bound. 
template <class T> struct is_trivially_default_constructible;  
template <class T> struct is_trivially_copy_constructible;  For a referenceable type T, the same result as
is_trivially_constructible_v<T, const T&>, otherwise false.  
template <class T> struct is_trivially_move_constructible;  For a referenceable type T, the same result as
is_trivially_constructible_v<T, T&&>, otherwise false.  
template <class T, class U> struct is_trivially_assignable;  is_assignable_v<T, U> is true and the assignment, as defined by
is_assignable, is known to call no operation that is not trivial
([basic.types], [special]).  
template <class T> struct is_trivially_copy_assignable;  For a referenceable type T, the same result as
is_trivially_assignable_v<T&, const T&>, otherwise false.  
template <class T> struct is_trivially_move_assignable;  For a referenceable type T, the same result as
is_trivially_assignable_v<T&, T&&>, otherwise false.  
template <class T> struct is_trivially_destructible;  
template <class T, class... Args> struct is_nothrow_constructible;  is_constructible_v<T, Args...> is true
and the
variable definition for is_constructible, as defined below, is known not to
throw any exceptions ([expr.unary.noexcept]).  T and all types in the parameter pack Args
shall be complete types, cv void,
or arrays of unknown bound. 
template <class T> struct is_nothrow_default_constructible;  
template <class T> struct is_nothrow_copy_constructible;  For a referenceable type T, the same result as
is_nothrow_constructible_v<T, const T&>, otherwise false.  
template <class T> struct is_nothrow_move_constructible;  For a referenceable type T, the same result as
is_nothrow_constructible_v<T, T&&>, otherwise false.  
template <class T, class U> struct is_nothrow_assignable;  is_assignable_v<T, U> is true and the assignment is known not to
throw any exceptions ([expr.unary.noexcept]).  
template <class T> struct is_nothrow_copy_assignable;  For a referenceable type T, the same result as
is_nothrow_assignable_v<T&, const T&>, otherwise false.  
template <class T> struct is_nothrow_move_assignable;  For a referenceable type T, the same result as
is_nothrow_assignable_v<T&, T&&>, otherwise false.  
template <class T, class U> struct is_nothrow_swappable_with;  is_swappable_with_v<T, U> is true and
each swap expression of the definition of
is_swappable_with<T, U> is known not to throw
any exceptions ([expr.unary.noexcept]).  
template <class T> struct is_nothrow_swappable;  For a referenceable type T,
the same result as is_nothrow_swappable_with_v<T&, T&>,
otherwise false.  
template <class T> struct is_nothrow_destructible;  is_destructible_v<T> is true and the indicated destructor is known
not to throw any exceptions ([expr.unary.noexcept]).  
template <class T> struct has_virtual_destructor;  T has a virtual destructor  
template <class T> struct has_unique_object_representations;  For an array type T, the same result as
has_unique_object_representations_v<remove_all_extents_t<T>>,
otherwise see below. 
Template  Value 
alignof(T).  
If T names an array type, an integer value representing
the number of dimensions of T; otherwise, 0.  
If T is not an array type, or if it has rank less
than or equal to I, or if I is 0 and T
has type “array of unknown bound of U”, then
0; otherwise, the bound ([dcl.array]) of the I'th dimension of
T, where indexing of I is zerobased 
Template  Condition  Comments 
template <class T, class U> struct is_same;  T and U name the same type with the same cvqualifications  
Base is a base class of Derived ([class.derived])
without regard to cvqualifiers
or Base and Derived are not unions and
name the same class type
without regard to cvqualifiers  If Base and
Derived are nonunion class types and are
not possibly cvqualified versions of the same type,
Derived shall be a complete
type.  
see below  
The expression INVOKE(declval<Fn>(), declval<ArgTypes>()...)
is wellformed when treated as an unevaluated operand  Fn and all types in the parameter pack ArgTypes
shall be complete types, cv void, or
arrays of unknown bound.  
The expression INVOKE<R>(declval<Fn>(), declval<ArgTypes>()...)
is wellformed when treated as an unevaluated operand  Fn, R, and all types in the parameter pack ArgTypes
shall be complete types, cv void, or
arrays of unknown bound.  
is_invocable_v< Fn, ArgTypes...> is true and the expression INVOKE(declval<Fn>(), declval<ArgTypes>()...) is known not to throw any exceptions  Fn and all types in the parameter pack ArgTypes
shall be complete types, cv void, or
arrays of unknown bound.  
is_invocable_r_v< R, Fn, ArgTypes...> is true and the expression INVOKE<R>(declval<Fn>(), declval<ArgTypes>()...) is known not to throw any exceptions  Fn, R, and all types in the parameter pack ArgTypes
shall be complete types, cv void, or
arrays of unknown bound. 
Template  Comments 
The member typedef type names
the same type as T
except that any toplevel constqualifier has been removed.  
The member typedef type names
the same type as T
except that any toplevel volatilequalifier has been removed.  
The member typedef type shall be the same as T
except that any toplevel cvqualifier has been removed.  
If T is a reference, function, or toplevel constqualified
type, then type names
the same type as T, otherwise
T const.  
If T is a reference, function, or toplevel volatilequalified
type, then type names
the same type as T, otherwise
T volatile.  
Template  Comments 
If T names a (possibly cvqualified)
signed integer type then the member typedef
type names the type T; otherwise,
if T names a (possibly cvqualified) unsigned integer
type then type names the corresponding
signed integer type, with the same cvqualifiers as T;
otherwise, type names the signed integer type with smallest
rank for which
sizeof(T) == sizeof(type), with the same
cvqualifiers as T.  
If T names a (possibly cvqualified)
unsigned integer type then the member typedef
type names the type T; otherwise,
if T names a (possibly cvqualified) signed integer
type then type names the corresponding
unsigned integer type, with the same cvqualifiers as T;
otherwise, type names the unsigned integer type with smallest
rank for which
sizeof(T) == sizeof(type), with the same
cvqualifiers as T. 
Template  Comments 
If T has type “(possibly cvqualified) pointer
to T1” then the member typedef type
names T1; otherwise, it names T.  
If T names a referenceable type or a
cv void type then
the member typedef type names the same type as
remove_reference_t<T>*;
otherwise, type names T. 
Template  Comments 
The value of defaultalignment shall be the most
stringent alignment requirement for any C++ object type whose size
is no greater than Len ([basic.types]). The member typedef type shall be a POD type
suitable for use as uninitialized storage for any object whose size
is at most Len and whose alignment is a divisor of Align.  
The member typedef type shall be a POD type suitable for use as
uninitialized storage for any object whose type is listed in Types;
its size shall be at least Len. The static member alignment_value
shall be an integral constant of type size_t whose value is the
strictest alignment of all types listed in Types.  
[ Note : ]This behavior is similar to the lvaluetorvalue,
arraytopointer, and functiontopointer
conversions applied when an lvalue expression is used as an rvalue, but also
strips cvqualifiers from class types in order to more closely model byvalue
argument passing. — end note  
template <bool B, class T,
class F> struct conditional;  
template <class... T> struct common_type;  Unless this trait is specialized (as specified in Note B, below),
the member type shall be defined or omitted as specified in Note A, below. If it is omitted, there shall be no member type. 
template <class Fn, class... ArgTypes> struct invoke_result;  If the expression INVOKE(declval<Fn>(), declval<ArgTypes>()...)
is wellformed when treated as an unevaluated operand,
the member typedef type names the type
decltype(INVOKE(declval<Fn>(), declval<ArgTypes>()...));
otherwise, there shall be no member type. Only the validity of the immediate context of the
expression is considered. [ Note : ]The compilation of the expression can result in side effects such as
the instantiation of class template specializations and function
template specializations, the generation of implicitlydefined
functions, and so on. Such side effects are not in the “immediate
context” and can result in the program being illformed. — end noteRequires: Fn and all types in the parameter pack ArgTypes shall be complete types, cv void, or arrays of unknown bound. 
Type  Value of X  Value of Y 
ratio_add<R1, R2>  R1::num * R2::den +  R1::den * R2::den 
R2::num * R1::den  
ratio_subtract<R1, R2>  R1::num * R2::den   R1::den * R2::den 
R2::num * R1::den  
ratio_multiply<R1, R2>  R1::num * R2::num  R1::den * R2::den 
ratio_divide<R1, R2>  R1::num * R2::den  R1::den * R2::num 
Expression  Return type  Operational semantics 
C1::rep  An arithmetic type or a class emulating an arithmetic type  The representation type of C1::duration. 
C1::period  a specialization of ratio  The tick period of the clock in seconds. 
C1::duration  chrono::duration<C1::rep, C1::period>  The duration type of the clock. 
C1::time_point  chrono::time_point<C1> or chrono::time_point<C2, C1::duration>  The time_point type of the clock. 
C1::is_steady  const bool  
C1::now()  C1::time_point  Returns a time_point object representing the current point in time. 
Subclause  Header(s)  
Character traits  <string>  
String classes  <string>  
String view classes  <string_view>  
<cctype>  
<cwctype>  
Nullterminated sequence utilities  <cstring>  
<cwchar>  
<cstdlib>  
<cuchar> 
Expression  Return type  Assertion/note  Complexity 
pre/postcondition  
X::char_type  charT  (described in [char.traits.typedefs])  compiletime 
X::int_type  (described in [char.traits.typedefs])  compiletime  
X::off_type  (described in [char.traits.typedefs])  compiletime  
X::pos_type  (described in [char.traits.typedefs])  compiletime  
X::state_type  (described in [char.traits.typedefs])  compiletime  
X::eq(c,d)  bool  constant  
X::lt(c,d)  bool  constant  
X::compare(p,q,n)  int  Returns: 0 if for each i in [0,n), X::eq(p[i],q[i])
is true; else, a negative value if, for some j in [0,n),
X::lt(p[j],q[j]) is true and for each i in [0,j)
X::eq(p[i],q[i]) is true; else a positive value.  linear 
X::length(p)  size_t  linear  
X::find(p,n,c)  const X::char_type*  linear  
X::move(s,p,n)  X::char_type*  linear  
X::copy(s,p,n)  X::char_type*  linear  
X::assign(r,d)  (not used)  assigns r=d.  constant 
X::assign(s,n,c)  X::char_type*  linear  
X::not_eof(e)  int_type  Returns: e if X::eq_int_type(e,X::eof()) is false,
otherwise a value f such that
X::eq_int_type(f,X::eof()) is false.  constant 
X::to_char_type(e)  X::char_type  Returns: if for some c, X::eq_int_type(e,X::to_int_type(c))
is true, c; else some unspecified value.  constant 
X::to_int_type(c)  X::int_type  constant  
X::eq_int_type(e,f)  bool  Returns: for all c and d, X::eq(c,d) is equal to
X::eq_int_type(X::to_int_type(c), X::to_int_type(d)); otherwise, yields true
if e and f are both copies of X::eof(); otherwise, yields false if
one of e and f is a copy of X::eof() and the other is not; otherwise
the value is unspecified.  constant 
X::eof()  X::int_type  constant 
Element  Value 
data()  a nonnull pointer that is copyable and can have 0 added to it 
size()  0 
capacity()  an unspecified value 
Element  Value 
data()  points at the first element of an allocated
copy of the array whose first element is
pointed at by str.data() 
size()  str.size() 
capacity()  a value at least as large as size() 
Element  Value 
data()  points at the first element of an allocated copy of rlen consecutive elements
of the string controlled by str beginning at position pos 
size()  rlen 
capacity()  a value at least as large as size() 
Element  Value 
data()  points at the first element of an allocated copy of the array whose first element
is pointed at by s 
size()  n 
capacity()  a value at least as large as size() 
Element  Value 
data()  points at the first element of an allocated copy of the array whose first element
is pointed at by s 
size()  traits::length(s) 
capacity()  a value at least as large as size() 
Element  Value 
data()  points at the first element of an allocated array of n elements, each
storing the initial value c 
size()  n 
capacity()  a value at least as large as size() 
Element  Value 
data()  points at the first element of an allocated copy of the array whose first
element is pointed at by the original value of str.data(). 
size()  the original value of str.size() 
capacity()  a value at least as large as size() 
get_allocator()  alloc 
Element  Value 
data()  points at the first element of an allocated copy of the array whose first
element is pointed at by str.data() 
size()  str.size() 
capacity()  a value at least as large as size() 
Condition  Return Value 
size() < sv.size()  < 0 
size() == sv.size()  0 
size() > sv.size()  > 0 
Element  Value 
data_  str 
size_  traits::length(str) 
Condition  Return Value 
size() < str.size()  < 0 
size() == str.size()  0 
size() > str.size()  > 0 
Expression  Equivalent to 
t == sv  S(t) == sv 
sv == t  sv == S(t) 
t != sv  S(t) != sv 
sv != t  sv != S(t) 
t < sv  S(t) < sv 
sv < t  sv < S(t) 
t > sv  S(t) > sv 
sv > t  sv > S(t) 
t <= sv  S(t) <= sv 
sv <= t  sv <= S(t) 
t >= sv  S(t) >= sv 
sv >= t  sv >= S(t) 
Subclause  Header(s)  
Locales  <locale>  
Standard locale Categories  
C library locales  <clocale> 
Category  Includes facets 
collate  collate<char>, collate<wchar_t> 
ctype  ctype<char>, ctype<wchar_t> 
codecvt<char, char, mbstate_t>  
codecvt<char16_t, char, mbstate_t>  
codecvt<char32_t, char, mbstate_t>  
codecvt<wchar_t, char, mbstate_t>  
monetary  moneypunct<char>, moneypunct<wchar_t> 
moneypunct<char, true>, moneypunct<wchar_t, true>  
money_get<char>, money_get<wchar_t>  
money_put<char>, money_put<wchar_t>  
numeric  numpunct<char>, numpunct<wchar_t> 
num_get<char>, num_get<wchar_t>  
num_put<char>, num_put<wchar_t>  
time  time_get<char>, time_get<wchar_t> 
time_put<char>, time_put<wchar_t>  
messages  messages<char>, messages<wchar_t> 
Category  Includes facets 
collate  collate_byname<char>, collate_byname<wchar_t> 
ctype  ctype_byname<char>, ctype_byname<wchar_t> 
codecvt_byname<char, char, mbstate_t>  
codecvt_byname<char16_t, char, mbstate_t>  
codecvt_byname<char32_t, char, mbstate_t>  
codecvt_byname<wchar_t, char, mbstate_t>  
monetary  moneypunct_byname<char, International> 
moneypunct_byname<wchar_t, International>  
money_get<C, InputIterator>  
money_put<C, OutputIterator>  
numeric  numpunct_byname<char>, numpunct_byname<wchar_t> 
num_get<C, InputIterator>, num_put<C, OutputIterator>  
time  time_get<char, InputIterator> 
time_get_byname<char, InputIterator>  
time_get<wchar_t, InputIterator>  
time_get_byname<wchar_t, InputIterator>  
time_put<char, OutputIterator>  
time_put_byname<char, OutputIterator>  
time_put<wchar_t, OutputIterator>  
time_put_byname<wchar_t, OutputIterator>  
messages  messages_byname<char>, messages_byname<wchar_t> 
Value  Meaning 
ok  completed the conversion 
partial  not all source characters converted 
error  encountered a character in [from, from_end)
that it could not convert 
noconv  internT and externT are the same type, and input
sequence is identical to converted sequence 
Value  Meaning 
ok  completed the sequence 
partial  space for more than to_end  to destination elements was needed
to terminate a sequence given the value of state 
error  an unspecified error has occurred 
noconv  no termination is needed for this state_type 
State  stdio equivalent 
basefield == oct  %o 
basefield == hex  %X 
basefield == 0  %i 
signed integral type  %d 
unsigned integral type  %u 
Type  Length modifier 
short  h 
unsigned short  h 
long  l 
unsigned long  l 
long long  ll 
unsigned long long  ll 
double  l 
long double  L 
State  stdio equivalent 
basefield == ios_base::oct  %o 
(basefield == ios_base::hex) && !uppercase  %x 
(basefield == ios_base::hex)  %X 
for a signed integral type  %d 
for an unsigned integral type  %u 
State  stdio equivalent 
floatfield == ios_base::fixed  %f 
floatfield == ios_base::scientific && !uppercase  %e 
floatfield == ios_base::scientific  %E 
floatfield == (ios_base::fixed  ios_base::scientific) && !uppercase  %a 
floatfield == (ios_base::fixed  ios_base::scientific)  %A 
!uppercase  %g 
otherwise  %G 
Type  Length modifier 
long  l 
long long  ll 
unsigned long  l 
unsigned long long  ll 
long double  L 
otherwise  none 
Type(s)  State  stdio equivalent 
an integral type  showpos  + 
showbase  #  
a floatingpoint type  showpos  + 
showpoint  # 
State  Location 
adjustfield == ios_base::left  pad after 
adjustfield == ios_base::right  pad before 
adjustfield == internal and a sign occurs in the representation  pad after the sign 
adjustfield == internal and representation after stage 1
began with 0x or 0X  pad after x or X 
otherwise  pad before 
date_order()  Format 
no_order  "%m%d%y" 
dmy  "%d%m%y" 
mdy  "%m%d%y" 
ymd  "%y%m%d" 
ydm  "%y%d%m" 
fprintf  isprint  iswdigit  localeconv  tolower 
fscanf  ispunct  iswgraph  mblen  toupper 
isalnum  isspace  iswlower  mbstowcs  towlower 
isalpha  isupper  iswprint  mbtowc  towupper 
isblank  iswalnum  iswpunct  setlocale  wcscoll 
iscntrl  iswalpha  iswspace  strcoll  wcstod 
isdigit  iswblank  iswupper  strerror  wcstombs 
isgraph  iswcntrl  iswxdigit  strtod  wcsxfrm 
islower  iswctype  isxdigit  strxfrm  wctomb 
Subclause  Header(s)  
Requirements  
Sequence containers  <array>  
<deque>  
<forward_list>  
<list>  
<vector>  
Associative containers  <map>  
<set>  
Unordered associative containers  <unordered_map>  
<unordered_set>  
Container adaptors  <queue>  
<stack> 
Expression  Return type  Operational  Assertion/note  Complexity 
semantics  pre/postcondition  
X::value_type  T  compile time  
X::reference  T&  compile time  
X::const_reference  const T&  compile time  
X::iterator  iterator type whose value type is T  any iterator category
that meets the forward iterator requirements. convertible to X::const_iterator.  compile time  
X::const_iterator  constant iterator type whose value type is T  any iterator category
that meets the forward iterator requirements.  compile time  
X::difference_type  signed integer type  is identical to the difference type of X::iterator and X::const_iterator  compile time  
X::size_type  unsigned integer type  size_type can represent any nonnegative value of difference_type  compile time  
X u;  Postconditions: u.empty()  constant  
X()  Postconditions: X().empty()  constant  
X(a)  linear  
X u(a); X u = a;  Postconditions: u == a  linear  
X u(rv); X u = rv;  Postconditions: u shall be equal to the value that rv had before this construction  (Note B)  
a = rv  X&  All existing elements of a are either move assigned to or destroyed  a shall be equal to the value that rv
had before this assignment  linear 
(&a)>~X()  void  the destructor is applied to every element of a; any memory obtained is deallocated.  linear  
a.begin()  iterator; const_iterator for constant a  constant  
a.end()  iterator; const_iterator for constant a  constant  
a.cbegin()  const_iterator  const_cast<X const&>(a).begin();  constant  
a.cend()  const_iterator  const_cast<X const&>(a).end();  constant  
a == b  convertible to bool  == is an equivalence relation. equal(a.begin(), a.end(), b.begin(), b.end())  Requires: T is EqualityComparable  Constant if a.size() != b.size(),
linear otherwise 
a != b  convertible to bool  Equivalent to !(a == b)  linear  
a.swap(b)  void  exchanges the contents of a and b  (Note A)  
swap(a, b)  void  a.swap(b)  (Note A)  
r = a  X&  linear  
a.size()  size_type  distance(a.begin(), a.end())  constant  
a.max_size()  size_type  distance(begin(), end())
for the largest possible container  constant  
a.empty()  convertible to bool  a.begin() == a.end()  constant 
Expression  Return type  Assertion/note  Complexity 
pre/postcondition  
X::reverse_iterator  iterator type whose value type is T  reverse_iterator<iterator>  compile time 
X::const_reverse_iterator  constant iterator type whose value type is T  reverse_iterator<const_iterator>  compile time 
a.rbegin()  reverse_iterator; const_reverse_iterator for constant a  reverse_iterator(end())  constant 
a.rend()  reverse_iterator; const_reverse_iterator for constant a  reverse_iterator(begin())  constant 
a.crbegin()  const_reverse_iterator  const_cast<X const&>(a).rbegin()  constant 
a.crend()  const_reverse_iterator  const_cast<X const&>(a).rend()  constant 
Expression  Return type  Operational  Assertion/note  Complexity 
semantics  pre/postcondition  
a < b  convertible to bool  lexicographical_compare( a.begin(), a.end(), b.begin(), b.end())  < is a total ordering relationship.  linear 
a > b  convertible to bool  b < a  linear  
a <= b  convertible to bool  !(a > b)  linear  
a >= b  convertible to bool  !(a < b)  linear 
Expression  Return type  Assertion/note  Complexity 
pre/postcondition  
allocator_type  A  compile time  
get_ allocator()  A  constant  
X() X u;  Postconditions: u.empty() returns true, u.get_allocator() == A()  constant  
X(m)  Postconditions: u.empty() returns true,  constant  
X u(m);  u.get_allocator() == m  
X(t, m) X u(t, m);  Postconditions: u == t, u.get_allocator() == m  linear  
X(rv) X u(rv);  Postconditions: u shall have the same elements as rv had before this
construction; the value of u.get_allocator() shall be the same as the
value of rv.get_allocator() before this construction.  constant  
X(rv, m) X u(rv, m);  Postconditions: u shall have the same elements, or copies of the elements, that rv had before this construction, u.get_allocator() == m  constant if m == rv.get_allocator(), otherwise linear  
a = t  X&  Postconditions: a == t  linear 
a = rv  X&  Requires: If allocator_ traits<allocator_type> ::propagate_on_container_ move_assignment::value is false, T is MoveInsertable into X and MoveAssignable. All existing elements of a
are either move assigned to or destroyed.  linear 
a.swap(b)  void  exchanges the contents of a and b  constant 
Expression  Return type  Assertion/note 
pre/postcondition  
X(n, t) X u(n, t);  Postconditions: distance(begin(), end()) == n Constructs a sequence container with n copies of t  
X(i, j) X u(i, j);  For vector, if the iterator does
not meet the forward iterator requirements, T
shall also be
MoveInsertable into X. Each iterator in the range [i, j) shall be dereferenced exactly once. Postconditions: distance(begin(), end()) == distance(i, j) Constructs a sequence container equal to the range [i, j)  
X(il)  Equivalent to X(il.begin(), il.end())  
a = il  X&  All existing
elements of a are either assigned to or destroyed. 
a.emplace(p, args)  iterator  
a.insert(p,t)  iterator  
a.insert(p,rv)  iterator  
a.insert(p,n,t)  iterator  
a.insert(p,i,j)  iterator  For vector and deque, T shall also be
MoveInsertable into X, MoveConstructible, MoveAssignable,
and swappable. Each iterator in the range [i, j) shall be dereferenced exactly once. Inserts copies of elements in [i, j) before p 
a.insert(p, il)  iterator  a.insert(p, il.begin(), il.end()). 
a.erase(q)  iterator  
a.erase(q1,q2)  iterator  
a.clear()  void  Destroys all elements in a. Invalidates all references, pointers, and
iterators referring to the elements of a and may invalidate the pasttheend iterator. 
a.assign(i,j)  void  For vector, if the iterator does not
meet the forward iterator requirements, T
shall also be
MoveInsertable into X. 
a.assign(il)  void  a.assign(il.begin(), il.end()). 
a.assign(n,t)  void 
Expression  Return type  Operational semantics  Container 
a.front()  reference; const_reference for constant a  *a.begin()  basic_string,
array,
deque,
forward_list,
list,
vector 
a.back()  reference; const_reference for constant a  { auto tmp = a.end(); tmp; return *tmp; }  basic_string,
array,
deque,
list,
vector 
a.emplace_front(args)  reference  deque,
forward_list,
list  
a.emplace_back(args)  reference  deque,
list,
vector  
a.push_front(t)  void  Prepends a copy of t.  deque,
forward_list,
list 
a.push_front(rv)  void  Prepends a copy of rv.  deque,
forward_list,
list 
a.push_back(t)  void  Appends a copy of t.  basic_string,
deque,
list,
vector 
a.push_back(rv)  void  Appends a copy of rv.  basic_string,
deque,
list,
vector 
a.pop_front()  void  Destroys the first element.  deque,
forward_list,
list 
a.pop_back()  void  Destroys the last element.  basic_string,
deque,
list,
vector 
a[n]  reference; const_reference for constant a  *(a.begin() + n)  basic_string,
array,
deque,
vector 
a.at(n)  reference; const_reference for constant a  *(a.begin() + n)  basic_string,
array,
deque,
vector 
map<K, T, C1, A>  map<K, T, C2, A> 
map<K, T, C1, A>  multimap<K, T, C2, A> 
set<K, C1, A>  set<K, C2, A> 
set<K, C1, A>  multiset<K, C2, A> 
unordered_map<K, T, H1, E1, A>  unordered_map<K, T, H2, E2, A> 
unordered_map<K, T, H1, E1, A>  unordered_multimap<K, T, H2, E2, A> 
unordered_set<K, H1, E1, A>  unordered_set<K, H2, E2, A> 
unordered_set<K, H1, E1, A>  unordered_multiset<K, H2, E2, A> 
Expression  Return type  Assertion/note  Complexity 
pre/postcondition  
X::key_type  Key  compile time  
X::mapped_type (map and multimap only)  T  compile time  
X::value_type (set and multiset only)  Key  Requires: value_type is Erasable from X  compile time 
X::value_type (map and multimap only)  pair<const Key, T>  Requires: value_type is Erasable from X  compile time 
X::key_compare  Compare  compile time  
X::value_compare  a binary predicate type  is the same as key_compare for set and
multiset; is an ordering relation on pairs induced by the
first component (i.e., Key) for map and multimap.  compile time 
X::node_type  a specialization of a node_handle
class template, such that the public nested types are
the same types as the corresponding types in X.  see [container.node]  compile time 
X(c) X u(c);  Effects: Constructs an empty container. Uses a copy of c as a comparison object.  constant  
X() X u;  Uses Compare() as a comparison object  constant  
X(i,j,c) X u(i,j,c);  Effects: Constructs an empty container and inserts elements from the range [i, j) into it; uses c as a comparison object.  in general, where N has the value distance(i, j);
linear if [i, j) is sorted with value_comp()  
X(i,j) X u(i,j);  same as above  
X(il)  same as X(il.begin(), il.end())  same as X(il.begin(), il.end())  
X(il,c)  same as X(il.begin(), il.end(), c)  same as X(il.begin(), il.end(), c)  
a = il  X&  All
existing elements of a are either assigned to or destroyed.  in general, where N has the value il.size() + a.size();
linear if [il.begin(), il.end()) is sorted with value_comp() 
b.key_comp()  X::key_compare  returns the comparison object out of which b was constructed.  constant 
b.value_comp()  X::value_compare  returns an object of value_compare constructed out of the comparison object  constant 
a_uniq.emplace(args)  pair<iterator, bool>  Effects: Inserts a value_type object t constructed with std::forward<Args>(args)... if and only if there is no element in the container with key equivalent to the key of t. The bool component of the returned
pair is true if and only if the insertion takes place, and the iterator
component of the pair points to the element with key equivalent to the
key of t.  logarithmic 
a_eq.emplace(args)  iterator  Effects: Inserts a value_type object t constructed with std::forward<Args>(args)... and returns the iterator pointing to the newly inserted element. If a range containing elements equivalent to t exists in a_eq,
t is inserted at the end of that range.  logarithmic 
a.emplace_hint(p, args)  iterator  Return value is an iterator pointing to the element with the key equivalent
to the newly inserted element. The element is inserted as close as possible to the position just prior
to p.  logarithmic in general, but amortized constant if the element
is inserted right before p 
a_uniq.insert(t)  pair<iterator, bool>  Requires: If t is a nonconst rvalue expression, value_type shall be
MoveInsertable into X; otherwise, value_type shall be
CopyInsertable into X. Effects: Inserts t if and only if there is no element in the container with key equivalent to the key of t. The bool component of
the returned pair is true if and only if the insertion
takes place, and the iterator
component of the pair points to the element with key
equivalent to the key of t.  logarithmic 
a_eq.insert(t)  iterator  Requires: If t is a nonconst rvalue expression, value_type shall be
MoveInsertable into X; otherwise, value_type shall be
CopyInsertable into X. If a range containing elements equivalent to
t exists in a_eq, t
is inserted at the end of that range.  logarithmic 
a.insert(p, t)  iterator  Requires: If t is a nonconst rvalue expression, value_type shall be
MoveInsertable into X; otherwise, value_type shall be
CopyInsertable into X. Effects: Inserts t if and only if there is no element with key equivalent to the key of t in containers with unique keys; always inserts t in containers with equivalent keys. Always
returns the iterator pointing to the element with key equivalent to
the key of t.  
a.insert(i, j)  void  inserts each element from the range [i, j) if and only if there
is no element with key equivalent to the key of that element in containers
with unique keys; always inserts that element in containers with equivalent keys.  , where N has the value distance(i, j) 
a.insert(il)  void  equivalent to a.insert(il.begin(), il.end())  
a_uniq.insert(nh)  insert_return_type  Otherwise, inserts the
element owned by nh if and only if there is no element in the
container with a key equivalent to nh.key(). Otherwise if the insertion took place, inserted is true,
position points to the inserted element, and node is empty;
if the insertion failed, inserted is false,
node has the previous value of nh, and position
points to an element with a key equivalent to nh.key().  logarithmic 
a_eq.insert(nh)  iterator  Otherwise, inserts the element owned by nh and returns an iterator
pointing to the newly inserted element. If a range containing elements with
keys equivalent to nh.key() exists in a_eq, the element is
inserted at the end of that range.  logarithmic 
a.insert(p, nh)  iterator  Otherwise, inserts the element owned by nh if and only if there
is no element with key equivalent to nh.key() in containers with
unique keys; always inserts the element owned by nh in containers
with equivalent keys. Always returns the iterator pointing to the element
with key equivalent to nh.key(). The element is inserted as close
as possible to the position just prior to p.  logarithmic in general, but amortized constant if the element is inserted right
before p. 
a.extract(k)  node_type  removes the first element in the container with key equivalent to k.  log(a.size()) 
a.extract(q)  node_type  removes the element pointed to by q. Returns a node_type owning that element.  amortized constant 
a.merge(a2)  void  In containers with unique keys,
if there is an element in a with key equivalent to the key of an
element from a2, then that element is not extracted from a2. Postconditions: Pointers and references to the transferred elements of a2 refer to those same elements but as members of a. Iterators referring
to the transferred elements will continue to refer to their elements, but
they now behave as iterators into a, not into a2.  
a.erase(k)  size_type  erases all elements in the container with key equivalent to
k. returns the number of erased elements.  
a.erase(q)  iterator  erases the element pointed to by q. Returns an iterator pointing to
the element immediately following q prior to the element being erased. If no such element exists, returns a.end().  amortized constant 
a.erase(r)  iterator  erases the element pointed to by r. Returns an iterator pointing to
the element immediately following r prior to the element being erased. If no such element exists, returns a.end().  amortized constant 
a.erase( q1, q2)  iterator  erases all the elements in the range [q1, q2). Returns an iterator pointing to
the element pointed to by q2 prior to any elements being erased. If no such element
exists, a.end() is returned.  
a.clear()  void  linear in a.size().  
b.find(k)  returns an iterator pointing to an element with the key equivalent
to k, or b.end() if such an element is not found  logarithmic  
a_tran. find(ke)  returns an iterator pointing to an element with key r such that
!c(r, ke) && !c(ke, r), or a_tran.end() if such an element
is not found  logarithmic  
b.count(k)  size_type  returns the number of elements with key equivalent to k  
a_tran. count(ke)  size_type  returns the number of elements with key r such that
!c(r, ke) && !c(ke, r)  
b.lower_bound(k)  returns an iterator pointing to the first element with
key not less than k,
or b.end() if such an element is not found.  logarithmic  
a_tran. lower_bound(kl)  returns an iterator pointing to the first element with
key r such that !c(r, kl),
or a_tran.end() if such an element is not found.  logarithmic  
b.upper_bound(k)  returns an iterator pointing to the first element with
key greater than k,
or b.end() if such an element is not found.  logarithmic  
a_tran. upper_bound(ku)  returns an iterator pointing to the first element with
key r such that c(ku, r),
or a_tran.end() if such an element is not found.  logarithmic  
b.equal_range(k)  equivalent to make_pair(b.lower_bound(k), b.upper_bound(k)).  logarithmic  
a_tran. equal_range(ke)  logarithmic 
Expression  Return type  Assertion/note  Complexity 
pre/postcondition  
X::key_type  compile time  
X::mapped_type (unordered_map and unordered_multimap only)  T  compile time  
X::value_type (unordered_set and unordered_multiset only)  Key  Requires: value_type is Erasable from X  compile time 
X::value_type (unordered_map and unordered_multimap only)  pair<const Key, T>  Requires: value_type is Erasable from X  compile time 
X::hasher  Hash  compile time  
X::key_equal  Pred  Pred is an equivalence relation.  compile time 
X::local_iterator  An iterator type whose category, value type,
difference type, and pointer and reference types are the same as
X::iterator's.  A local_iterator object may be used to iterate through a
single bucket, but may not be used to iterate across
buckets.  compile time 
X::const_local_iterator  An iterator type whose category, value type,
difference type, and pointer and reference types are the same as
X::const_iterator's.  A const_local_iterator object may be used to iterate through a
single bucket, but may not be used to iterate across
buckets.  compile time 
X::node_type  a specialization of a node_handle
class template, such that the public nested types are
the same types as the corresponding types in X.  see [container.node]  compile time 
X(n, hf, eq) X a(n, hf, eq);  X  Effects: Constructs an empty container with at least n buckets,
using hf as the hash function and eq as the key
equality predicate.  
X(n, hf) X a(n, hf);  X  Effects: Constructs an empty container with at least n buckets, using hf as the hash function and key_equal() as the key equality predicate.  
X(n) X a(n);  X  Effects: Constructs an empty container with at least n buckets, using hasher() as the hash function and key_equal() as the key equality predicate.  
X() X a;  X  Effects: Constructs an empty container with an unspecified number of buckets, using hasher() as the hash function and key_equal() as the key equality predicate.  constant 
X(i, j, n, hf, eq) X a(i, j, n, hf, eq);  X  Effects: Constructs an empty container with at least n buckets, using hf as the hash function and eq as the key equality predicate, and inserts elements from [i, j) into it.  Average case (N is distance(i, j)), worst case

X(i, j, n, hf) X a(i, j, n, hf);  X  Effects: Constructs an empty container with at least n buckets, using hf as the hash function and key_equal() as the key equality predicate, and inserts elements from [i, j) into it.  Average case (N is distance(i, j)), worst case

X(i, j, n) X a(i, j, n);  X  Effects: Constructs an empty container with at least n buckets, using hasher() as the hash function and key_equal() as the key equality predicate, and inserts elements from [i, j) into it.  Average case (N is distance(i, j)), worst case

X(i, j) X a(i, j);  X  Effects: Constructs an empty container with an unspecified number of buckets, using hasher() as the hash function and key_equal() as the key equality predicate, and inserts elements from [i, j) into it.  Average case (N is distance(i, j)), worst case

X(il)  X  Same as X(il.begin(), il.end()).  
X(il, n)  X  Same as X(il.begin(), il.end(), n).  
X(il, n, hf)  X  Same as X(il.begin(), il.end(), n, hf).  
X(il, n, hf, eq)  X  Same as X(il.begin(), il.end(), n, hf, eq).  
X(b) X a(b);  X  Copy constructor.  Average case linear in b.size(), worst case quadratic. 
a = b  X&  Copy assignment operator.  Average case linear in b.size(), worst case quadratic. 
a = il  X&  All
existing elements of a are either assigned to or destroyed.  Same as a = X(il). 
b.hash_function()  hasher  Returns b's hash function.  constant 
b.key_eq()  key_equal  Returns b's key equality predicate.  constant 
a_uniq. emplace(args)  pair<iterator, bool>  Effects: Inserts a value_type object t constructed with std::forward<Args>(args)... if and only if there is no element in the container with key equivalent to the key of t. The bool component of the returned
pair is true if and only if the insertion takes place, and the iterator
component of the pair points to the element with key equivalent to the
key of t.  
a_eq.emplace(args)  iterator  Effects: Inserts a value_type object t constructed with std::forward<Args>(args)... and returns the iterator pointing to the newly inserted element.  
a.emplace_hint(p, args)  iterator  Return value is an iterator pointing to the element with the key equivalent
to the newly inserted element. Implementations are
permitted to ignore the hint.  
a_uniq.insert(t)  pair<iterator, bool>  Requires: If t is a nonconst rvalue expression, value_type shall be
MoveInsertable into X; otherwise, value_type shall be
CopyInsertable into X. Effects: Inserts t if and only if there is no element in the container with key equivalent to the key of t. The bool
component of the returned pair indicates whether the insertion
takes place, and the iterator component points to the element
with key equivalent to the key of t.  
a_eq.insert(t)  iterator  Requires: If t is a nonconst rvalue expression, value_type shall be
MoveInsertable into X; otherwise, value_type shall be
CopyInsertable into X.  
a.insert(p, t)  iterator  Requires: If t is a nonconst rvalue expression, value_type shall be
MoveInsertable into X; otherwise, value_type shall be
CopyInsertable into X. insert(t). Return value is an iterator pointing
to the element with the key equivalent to that of t. The
iterator p is a hint pointing to where the search should
start. Implementations are permitted to ignore the hint.  
a.insert(i, j)  void  Worst case .  
a.insert(il)  void  Same as a.insert(il.begin(), il.end()).  
a_uniq. insert(nh)  insert_return_type  Otherwise, inserts the
element owned by nh if and only if there is no element in the
container with a key equivalent to nh.key(). Otherwise if the insertion took place, inserted is true,
position points to the inserted element, and node is empty;
if the insertion failed, inserted is false,
node has the previous value of nh, and position
points to an element with a key equivalent to nh.key().  
a_eq. insert(nh)  iterator  Otherwise, inserts the element owned by nh and returns an iterator
pointing to the newly inserted element.  
a.insert(q, nh)  iterator  Otherwise, inserts the element owned by nh if and only if there
is no element with key equivalent to nh.key() in containers with
unique keys; always inserts the element owned by nh in containers
with equivalent keys. Always returns the iterator pointing to the element
with key equivalent to nh.key(). The iterator q is a hint
pointing to where the search should start. Implementations are permitted
to ignore the hint.  
a.extract(k)  node_type  Removes an element in the container with key equivalent to k.  
a.extract(q)  node_type  Removes the element pointed to by q. Returns a node_type owning that element.  
a.merge(a2)  void  Attempts to extract each element in a2 and insert it into a using the hash function and key equality predicate of a. In containers with unique keys, if there is an element in a with
key equivalent to the key of an element from a2, then that
element is not extracted from a2.
Postconditions: Pointers and references to the transferred elements of a2
refer to those same elements but as members of a. Iterators referring
to the transferred elements and all iterators referring to a will
be invalidated, but iterators to elements remaining in a2 will
remain valid.  Worst case . 
a.erase(k)  size_type  Erases all elements with key equivalent to k. Returns
the number of elements erased.  Average case . Worst case
. 
a.erase(q)  iterator  Erases the element pointed to by q. Returns the
iterator immediately following q prior to the erasure.  
a.erase(r)  iterator  Erases the element pointed to by r. Returns the
iterator immediately following r prior to the erasure.  
a.erase(q1, q2)  iterator  Erases all elements in the range [q1, q2). Returns
the iterator immediately following the erased elements prior to the
erasure.  
a.clear()  void  Erases all elements in the container.  Linear in a.size(). 
b.find(k)  Returns an iterator pointing to an element with key equivalent to
k, or b.end() if no such element exists.  
b.count(k)  size_type  Returns the number of elements with key equivalent to k.  
b.equal_range(k)  Returns a range containing all elements with keys equivalent to
k. Returns make_pair(b.end(), b.end()) if
no such elements exist.  Average case . Worst case
.  
b.bucket_count()  size_type  Returns the number of buckets that b contains.  Constant 
b.max_bucket_count()  size_type  Returns an upper bound on the number of buckets that b might
ever contain.  Constant 
b.bucket(k)  size_type  Returns the index of the bucket in which elements with keys equivalent to k would be found, if any such element existed.  Constant 
b.bucket_size(n)  size_type  Returns the number of elements in the bucket.  
b.begin(n)  b.begin(n) returns an iterator referring to the
first element in the bucket. If the bucket is empty, then
b.begin(n) == b.end(n).  Constant  
b.end(n)  b.end(n) returns an iterator which is the pasttheend
value for the bucket.  Constant  
b.cbegin(n)  const_local_iterator  Constant  
b.cend(n)  const_local_iterator  Constant  
b.load_factor()  float  Returns the average number of elements per bucket.  Constant 
b.max_load_factor()  float  Returns a positive number that the container attempts to keep the load factor
less than or equal to. The container automatically increases the
number of buckets as necessary to keep the load factor below this
number.  Constant 
a.max_load_factor(z)  void  May change the container's maximum load factor, using z as a hint.  Constant 
a.rehash(n)  void  Average case linear in a.size(), worst case quadratic.  
a.reserve(n)  void  Average case linear in a.size(), worst case quadratic. 
Subclause  Header(s)  
Requirements  
Iterator primitives  <iterator>  
Predefined iterators  
Stream iterators 
Expression  Return type  Operational  Assertion/note 
semantics  pre/postcondition  
*r  unspecified  
++r  X& 
Expression  Return type  Operational  Assertion/note 
semantics  pre/postcondition  
a != b  contextually convertible to bool  !(a == b)  
*a  reference, convertible to T  
a>m  (*a).m  
++r  X&  Postconditions: r is dereferenceable or r is pasttheend; any copies of the previous value of r are no longer required either to be dereferenceable or to be in the domain of ==.  
(void)r++  equivalent to (void)++r  
*r++  convertible to T  { T tmp = *r; ++r; return tmp; } 
Expression  Return type  Operational  Assertion/note 
semantics  pre/postcondition  
*r = o  result is not used  
++r  X&  &r == &++r.  
r++  convertible to const X&  { X tmp = r; ++r; return tmp; }  
*r++ = o  result is not used 
Expression  Return type  Operational  Assertion/note 
semantics  pre/postcondition  
r++  convertible to const X&  { X tmp = r; ++r; return tmp; }  
*r++  reference 
Expression  Return type  Operational  Assertion/note 
semantics  pre/postcondition  
r  X&  
r  convertible to const X&  { X tmp = r; r; return tmp; }  
*r  reference 
Expression  Return type  Operational  Assertion/note 
semantics  pre/postcondition  
r += n  X&  { difference_type m = n; if (m >= 0) while (m) ++r; else while (m++) r; return r; }  
a + n n + a  X  { X tmp = a; return tmp += n; }  a + n == n + a. 
r = n  X&  return r += n;  
a  n  X  { X tmp = a; return tmp = n; }  
b  a  difference_type  return n  
a[n]  convertible to reference  *(a + n)  
a < b  contextually
convertible to bool  b  a > 0  < is a total ordering relation 
a > b  contextually
convertible to bool  b < a  
a >= b  contextually
convertible to bool  !(a < b)  
a <= b  contextually
convertible to bool.  !(a > b) 
Subclause  Header(s)  
Nonmodifying sequence operations  
Mutating sequence operations  <algorithm>  
Sorting and related operations  
C library algorithms  <cstdlib> 
Subclause  Header(s)  
Definitions  
Requirements  
Floatingpoint environment  <cfenv>  
Complex numbers  <complex>  
Random number generation  <random>  
Numeric arrays  <valarray>  
Generalized numeric operations  <numeric>  
Mathematical functions for  <cmath>  
floatingpoint types  <cstdlib> 
Expression  Return type  Pre/postcondition  Complexity 
T  compiletime  
Creates a seed sequence
with the same initial state as all other defaultconstructed seed sequences
of type S.  constant  
Creates a seed sequence
having internal state
that depends on some or all of the bits
of the supplied sequence .  
Same as S(il.begin(), il.end()).  same as S(il.begin(), il.end())  
void  Does nothing if rb == re. Otherwise,
fills the supplied sequence
with 32bit quantities
that depend on the sequence supplied to the constructor
and possibly also depend on the history
of generate's previous invocations.  
size_t  The number of 32bit units
that would be copied
by a call to r.param.  constant  
void  Copies to the given destination
a sequence of 32bit units
that can be provided
to the constructor of a second object of type S,
and that would reproduce in that second object
a state indistinguishable
from the state of the first object. 
Expression  Return type  Pre/postcondition  Complexity 
T  compiletime  
T  amortized constant  
T  Denotes the least value potentially returned
by operator().  compiletime  
T  Denotes the greatest value potentially returned
by operator().  compiletime 
Expression  Return type  Pre/postcondition  Complexity 
Creates an engine
with the same initial state
as all other defaultconstructed engines
of type E.  
Creates an engine
that compares equal to x.  
Creates an engine
with initial state determined by s.  
Creates an engine
with an initial state
that depends on a sequence
produced by one call
to q.generate.  same as complexity of q.generate
called on a sequence
whose length is size of state  
void  same as E()  
void  same as E(s)  
void  same as E(q)  
T  per Table 103  
void  no worse than the complexity
of z consecutive calls e()  
bool  This operator is an equivalence relation. With and
as the infinite sequences of values
that would be generated
by repeated future calls
to x() and y(),
respectively,
returns true
if ;
else returns false.  
bool  !(x == y).  
reference to the type of os  With os.fmtflags set to
ios_base::decios_base::left
and the fill character set to the space character,
writes to os
the textual representation
of x's current state. In the output,
adjacent numbers are separated
by one or more space characters.  
reference to the type of is  With is.fmtflags
set to ios_base::dec,
sets v's state
as determined by reading its textual representation from is. If bad input is encountered,
ensures that v's state is unchanged by the operation
and
calls is.setstate(ios::failbit)
(which may throw ios::failure ([iostate.flags])). If a textual representation written via os << x
was subsequently read via is >> v,
then x == v
provided that there have been no intervening invocations
of x or of v. Requires:
is provides a textual representation
that was previously written
using an output stream
whose imbued locale
was the same as that of is,
and whose type's template specialization arguments
charT and traits
were respectively the same as those of is. 
Expression  Return type  Pre/postcondition  Complexity 
T  compiletime  
P  compiletime  
Creates a distribution whose behavior is indistinguishable
from that of any other newly defaultconstructed distribution
of type D.  constant  
Creates a distribution whose behavior is indistinguishable
from that of a distribution
newly constructed directly from the values used to construct p.  same as p's construction  
void  constant  
P  no worse than the complexity of D(p)  
void  no worse than the complexity of D(p)  
T  With ,
the sequence of numbers
returned by successive invocations
with the same object g
is randomly distributed
according to the associated
p(z {p})
or
function.  amortized constant number of invocations of g  
T  The sequence of numbers
returned by successive invocations
with the same objects g and p
is randomly distributed
according to the associated
p(z {p})
or
function.  amortized constant number of invocations of g  
T  Returns glb.  constant  
T  Returns lub.  constant  
bool  This operator is an equivalence relation. Returns true
if x.param() == y.param() and ,
where and are
the infinite sequences of values
that would be generated, respectively,
by repeated future calls
to x(g1) and y(g2)
whenever g1 == g2. Otherwise returns false.  constant  
bool  !(x == y).  same as x == y.  
reference to the type of os  
reference to the type of is  If bad input is encountered,
ensures that d is unchanged by the operation
and
calls is.setstate(ios::failbit)
(which may throw ios::failure ([iostate.flags])). Requires: is provides a textual representation
that was previously written
using an os whose imbued locale
and whose type's template specialization arguments
charT and traits
were the same as those of is. 
Subclause  Header(s)  
Requirements  
Forward declarations  <iosfwd>  
Standard iostream objects  <iostream>  
Iostreams base classes  <ios>  
Stream buffers  <streambuf>  
Formatting and manipulators  <istream>  
<ostream>  
<iomanip>  
String streams  <sstream>  
File streams  <fstream>  
File systems  <filesystem>  
C library files  <cstdio>  
<cinttypes> 
Element  Effect(s) if set 
boolalpha  insert and extract bool type in alphabetic format 
dec  converts integer input or generates integer output in decimal base 
fixed  generate floatingpoint output in fixedpoint notation 
hex  converts integer input or generates integer output in hexadecimal base 
internal  adds fill characters at a designated internal point in certain generated output,
or identical to right if no such point is designated 
left  adds fill characters on the right (final positions) of certain generated output 
oct  converts integer input or generates integer output in octal base 
right  adds fill characters on the left (initial positions) of certain generated output 
scientific  generates floatingpoint output in scientific notation 
showbase  generates a prefix indicating the numeric base of generated integer output 
showpoint  generates a decimalpoint character unconditionally in generated floatingpoint output 
showpos  generates a + sign in nonnegative generated numeric output 
skipws  skips leading whitespace before certain input operations 
unitbuf  flushes output after each output operation 
uppercase  replaces certain lowercase letters with their uppercase equivalents in generated output 
Constant  Allowable values 
adjustfield  left  right  internal 
basefield  dec  oct  hex 
floatfield  scientific  fixed 
Element  Effect(s) if set 
badbit  indicates a loss of integrity in an input or output sequence
(such as an irrecoverable read error from a file); 
eofbit  indicates that an input operation reached the end of an input sequence; 
failbit  indicates that an input operation failed to read the expected characters,
or that an output operation failed to generate the desired characters. 
Element  Effect(s) if set 
app  seek to end before each write 
ate  open and seek to end immediately after opening 
binary  perform input and output in binary mode (as opposed to text mode) 
in  open for input 
out  open for output 
trunc  truncate an existing stream when opening 
Element  Meaning 
beg  request a seek (for subsequent input or output) relative to the beginning of the stream 
cur  request a seek relative to the current position within the sequence 
end  request a seek relative to the current end of the sequence 
Expression  Return type  Operational  Assertion/note 
semantics  pre/postcondition  
P(i)  
P p(i); P p = i;  
P(o)  fpos  converts from offset  
O(p)  streamoff  converts to offset  P(O(p)) == p 
p == q  convertible to bool  == is an equivalence relation  
p != q  convertible to bool  !(p == q)  
q = p + o p += o  fpos  + offset  q  o == p 
q = p  o p = o  fpos   offset  q + o == p 
o = p  q  streamoff  distance  q + o == p 
streamsize(o) O(sz)  streamsize streamoff  converts converts  streamsize(O(sz)) == sz streamsize(O(sz)) == sz 
Element  Value 
rdbuf()  sb 
tie()  0 
rdstate()  
exceptions()  goodbit 
flags()  skipws  dec 
width()  0 
precision()  6 
fill()  widen(' ') 
getloc()  a copy of the value returned by locale() 
iarray  a null pointer 
parray  a null pointer 
Element  Value 
rdbuf()  unchanged 
tie()  rhs.tie() 
rdstate()  unchanged 
exceptions()  rhs.exceptions() 
flags()  rhs.flags() 
width()  rhs.width() 
precision()  rhs.precision() 
fill()  rhs.fill() 
getloc()  rhs.getloc() 
Conditions  Result 
(which & ios_base::in) == ios_base::in  positions the input sequence 
(which & ios_base::out) == ios_base::out  positions the output sequence 
(which & (ios_base::in  ios_base::out)) == (ios_base::in  ios_base::out) and way == either ios_base::beg or ios_base::end  positions both the input and the output sequences 
Otherwise  the positioning operation fails. 
Condition  newoff Value 
way == ios_base::beg  0 
way == ios_base::cur  the next pointer minus the beginning pointer (xnext  xbeg). 
way == ios_base::end  the high mark pointer minus the beginning pointer (high_mark  xbeg). 
ios_base flag combination  stdio equivalent  
binary  in  out  trunc  app  
+  "w"  
+  +  "a"  
+  "a"  
+  +  "w"  
+  "r"  
+  +  "r+"  
+  +  +  "w+"  
+  +  +  "a+"  
+  +  "a+"  
+  +  "wb"  
+  +  +  "ab"  
+  +  "ab"  
+  +  +  "wb"  
+  +  "rb"  
+  +  +  "r+b"  
+  +  +  +  "w+b"  
+  +  +  +  "a+b"  
+  +  +  "a+b" 
way Value  stdio Equivalent 
basic_ios::beg  SEEK_SET 
basic_ios::cur  SEEK_CUR 
basic_ios::end  SEEK_END 
Expression  Value 
runtime_error::what()  what_arg.c_str() 
code()  ec 
path1().empty()  true 
path2().empty()  true 
Expression  Value 
runtime_error::what()  what_arg.c_str() 
code()  ec 
path1()  Reference to stored copy of p1 
path2().empty()  true 
Expression  Value 
runtime_error::what()  what_arg.c_str() 
code()  ec 
path1()  Reference to stored copy of p1 
path2()  Reference to stored copy of p2 
Name  Meaning 
native_format  The native pathname format. 
generic_format  The generic pathname format. 
auto_format  The interpretation of the format of the character sequence is
implementationdefined. The implementation may inspect the content of the character sequence to
determine the format. 
Constant  Meaning 
none  The type of the file has not been determined or an error occurred while
trying to determine the type. 
not_found  Pseudotype indicating the file was not found. 
regular  Regular file 
directory  Directory file 
symlink  Symbolic link file 
block  Block special file 
character  Character special file 
fifo  FIFO or pipe file 
socket  Socket file 
unknown  The file exists but the type could not be determined 
Option group controlling copy_file function effects for existing target files  
Constant  Meaning 
none  (Default) Error; file already exists. 
skip_existing  Do not overwrite existing file, do not report an error. 
overwrite_existing  Overwrite the existing file. 
update_existing  Overwrite the existing file if it is older than the replacement file. 
Option group controlling copy function effects for subdirectories  
Constant  Meaning 
none  (Default) Do not copy subdirectories. 
recursive  Recursively copy subdirectories and their contents. 
Option group controlling copy function effects for symbolic links  
Constant  Meaning 
none  (Default) Follow symbolic links. 
copy_symlinks  Copy symbolic links as symbolic links rather than copying the files that
they point to. 
skip_symlinks  Ignore symbolic links. 
Option group controlling copy function effects for choosing the form of copying  
Constant  Meaning 
none  (Default) Copy content. 
directories_only  Copy directory structure only, do not copy nondirectory files. 
create_symlinks  Make symbolic links instead of copies of files. The source path shall be
an absolute path unless the destination path is in the current directory. 
create_hard_links  Make hard links instead of copies of files. 
Name  Value  POSIX  Definition or notes 
(octal)  macro  
none  0  There are no permissions set for the file.  
owner_read  0400  S_IRUSR  Read permission, owner 
owner_write  0200  S_IWUSR  Write permission, owner 
owner_exec  0100  S_IXUSR  Execute/search permission, owner 
owner_all  0700  S_IRWXU  Read, write, execute/search by owner; owner_read  owner_write  owner_exec 
group_read  040  S_IRGRP  Read permission, group 
group_write  020  S_IWGRP  Write permission, group 
group_exec  010  S_IXGRP  Execute/search permission, group 
group_all  070  S_IRWXG  Read, write, execute/search by group; group_read  group_write  group_exec 
others_read  04  S_IROTH  Read permission, others 
others_write  02  S_IWOTH  Write permission, others 
others_exec  01  S_IXOTH  Execute/search permission, others 
others_all  07  S_IRWXO  Read, write, execute/search by others; others_read  others_write  others_exec 
all  0777  owner_all  group_all  others_all  
set_uid  04000  S_ISUID  SetuserID on execution 
set_gid  02000  S_ISGID  SetgroupID on execution 
sticky_bit  01000  S_ISVTX  Operating system dependent. 
mask  07777  all  set_uid  set_gid  sticky_bit  
unknown  0xFFFF  The permissions are not known, such as when a file_status object
is created without specifying the permissions 
Name  Meaning 
replace  permissions shall replace the file's permission bits with perm 
add  permissions shall replace the file's permission bits with
the bitwise OR of perm and the file's current permission bits. 
remove  permissions shall replace the file's permission bits with
the bitwise AND of the complement of perm and the file's current permission bits. 
nofollow  permissions shall change the permissions of a symbolic link itself
rather than the permissions of the file the link resolves to. 
Name  Meaning 
none  (Default) Skip directory symlinks, permission denied is an error. 
follow_directory_symlink  Follow rather than skip directory symlinks. 
skip_permission_denied  Skip directories that would otherwise result in permission denied. 
Subclause  Header(s)  
Definitions  
Requirements  
Constants  
Exception type  
Traits  
Regular expression template  <regex>  
Submatches  
Match results  
Algorithms  
Iterators  
Grammar 
Expression  Return type  Assertion/note pre/postcondition 
X::char_type  charT  The character container type used in the implementation of class
template basic_regex. 
X::string_type  basic_string<charT>  
X::locale_type  A copy constructible type  A type that represents the locale used by the traits class. 
X::char_class_type  A bitmask type representing a particular character classification.  
X::length(p)  size_t  Complexity is
linear in i . 
v.translate(c)  X::char_type  Returns a character such that for any character d that is to
be considered equivalent to c then v.translate(c) == v.translate(d). 
v.translate_nocase(c)  X::char_type  For all characters C that are to be considered equivalent
to c when comparisons are to be performed without regard to
case, then v.translate_nocase(c) == v.translate_nocase(C). 
v.transform(F1, F2)  X::string_type  Returns a sort key for the character sequence designated by the
iterator range [F1, F2) such that if the character sequence
[G1, G2) sorts before the character sequence [H1, H2)
then v.transform(G1, G2) < v.transform(H1, H2). 
v.transform_primary(F1, F2)  X::string_type  Returns a sort key for the character sequence designated by the
iterator range [F1, F2) such that if the character sequence
[G1, G2) sorts before the character sequence [H1, H2)
when character case is not considered
then v.transform_primary(G1, G2) < v.transform_primary(H1, H2). 
v.lookup_collatename(F1, F2)  X::string_type  Returns a sequence of characters that represents the collating element
consisting of the character sequence designated by the iterator range
[F1, F2). Returns an empty string if the character sequence is not
a valid collating element. 
v.lookup_classname(F1, F2, b)  X::char_class_type  Converts the character sequence designated by the iterator range
[F1, F2) into a value of a bitmask type that can
subsequently be passed to isctype. Values returned from
lookup_classname can be bitwise or'ed together; the
resulting value represents membership in either of the
corresponding character classes. If b is true, the returned bitmask is suitable for
matching characters without regard to their case. The value returned shall be independent of the case of
the characters in the sequence. 
v.isctype(c, cl)  bool  Returns true if character c is a member of
one of the character classes designated by cl,
false otherwise. 
v.value(c, I)  int  Returns the value represented by the digit c in base
I if the character c is a valid digit in base I;
otherwise returns 1. 
u.imbue(loc)  X::locale_type  
v.getloc()  X::locale_type  Returns the current locale used by v, if any. 
Element  Effect(s) if set 
icase  Specifies that matching of regular expressions against a character
container sequence shall be performed without regard to case. 
nosubs  Specifies that no subexpressions shall be considered to be marked, so that
when a regular expression is matched against a
character container sequence, no subexpression matches shall be
stored in the supplied match_results structure. 
optimize  Specifies that the regular expression engine should pay more attention
to the speed with which regular expressions are matched, and less to
the speed with which regular expression objects are
constructed. Otherwise it has no detectable effect on the program
output. 
collate  Specifies that character ranges of the form "[ab]" shall be locale
sensitive. 
ECMAScript  Specifies that the grammar recognized by the regular expression engine
shall be that used by ECMAScript in ECMA262, as modified in [re.grammar]. 
basic  Specifies that the grammar recognized by the regular expression engine
shall be that used by basic regular expressions in POSIX, Base Definitions and
Headers, Section 9, Regular Expressions. 
extended  Specifies that the grammar recognized by the regular expression engine
shall be that used by extended regular expressions in POSIX, Base Definitions and
Headers, Section 9, Regular Expressions. 
awk  Specifies that the grammar recognized by the regular expression engine
shall be that used by the utility awk in POSIX. 
grep  Specifies that the grammar recognized by the regular expression engine
shall be that used by the utility grep in POSIX. 
egrep  Specifies that the grammar recognized by the regular expression engine
shall be that used by the utility grep when given the E
option in POSIX. 
multiline  Specifies that ^ shall match the beginning of a line and
$ shall match the end of a line,
if the ECMAScript engine is selected. 
Element  Effect(s) if set 
The first character in the sequence [first, last) shall be treated
as though it is not at the beginning of a line, so the character
^ in the regular expression shall not match [first, first).  
The last character in the sequence [first, last) shall be treated
as though it is not at the end of a line, so the character
"$" in the regular expression shall not match [last, last).  
If more than one match is possible then any match is an
acceptable result.  
The expression shall not match an empty
sequence.  
The expression shall only match a subsequence that begins at
first.  
first is a valid iterator position.When this flag is
set the flags match_not_bol and match_not_bow shall be ignored by the
regular expression algorithms and iterators.  
When a regular expression match is to be replaced by a
new string, the new string shall be constructed using the rules used by
the ECMAScript replace function in ECMA262,
part 15.5.4.11 String.prototype.replace. In
addition, during search and replace operations all nonoverlapping
occurrences of the regular expression shall be located and replaced, and
sections of the input that did not match the expression shall be copied
unchanged to the output string.  
During a search and replace operation, sections of
the character container sequence being searched that do not match the
regular expression shall not be copied to the output string.  
When specified during a search and replace operation, only the
first occurrence of the regular expression shall be replaced. 
Value  Error condition 
error_collate  The expression contained an invalid collating element name. 
error_ctype  The expression contained an invalid character class name. 
error_escape  The expression contained an invalid escaped character, or a trailing
escape. 
error_backref  The expression contained an invalid back reference. 
error_brack  
error_paren  
error_brace  The expression contained mismatched { and } 
error_badbrace  The expression contained an invalid range in a {} expression. 
error_range  The expression contained an invalid character range, such as
[ba] in most encodings. 
error_space  There was insufficient memory to convert the expression into a finite
state machine. 
error_badrepeat  One of *?+{ was not preceded by a valid regular expression. 
error_complexity  The complexity of an attempted match against a regular expression
exceeded a preset level. 
error_stack  There was insufficient memory to determine whether the regular
expression could match the specified character sequence. 
Narrow character name  Wide character name  Corresponding ctype_base::mask value 
"alnum"  L"alnum"  ctype_base::alnum 
"alpha"  L"alpha"  ctype_base::alpha 
"blank"  L"blank"  ctype_base::blank 
"cntrl"  L"cntrl"  ctype_base::cntrl 
"digit"  L"digit"  ctype_base::digit 
"d"  L"d"  ctype_base::digit 
"graph"  L"graph"  ctype_base::graph 
"lower"  L"lower"  ctype_base::lower 
"print"  L"print"  ctype_base::print 
"punct"  L"punct"  ctype_base::punct 
"space"  L"space"  ctype_base::space 
"s"  L"s"  ctype_base::space 
"upper"  L"upper"  ctype_base::upper 
"w"  L"w"  ctype_base::alnum 
"xdigit"  L"xdigit"  ctype_base::xdigit 
Element  Value 
ready()  m.ready() 
size()  m.size() 
str(n)  m.str(n) for all integers n < m.size() 
prefix()  m.prefix() 
suffix()  m.suffix() 
(*this)[n]  m[n] for all integers n < m.size() 
length(n)  m.length(n) for all integers n < m.size() 
position(n)  m.position(n) for all integers n < m.size() 
Element  Value 
m.size()  1 + e.mark_count() 
m.empty()  false 
m.prefix().first  first 
m.prefix().second  first 
m.prefix().matched  false 
m.suffix().first  last 
m.suffix().second  last 
m.suffix().matched  false 
m[0].first  first 
m[0].second  last 
m[0].matched  true 
m[n].first  
m[n].second  
m[n].matched  For all integers 0 < n < m.size(), true if subexpression n participated in
the match, false otherwise. 
Element  Value 
m.size()  1 + e.mark_count() 
m.empty()  false 
m.prefix().first  first 
m.prefix().second  m[0].first 
m.prefix().matched  m.prefix().first != m.prefix().second 
m.suffix().first  m[0].second 
m.suffix().second  last 
m.suffix().matched  m.suffix().first != m.suffix().second 
m[0].first  The start of the sequence of characters that matched the regular expression 
m[0].second  The end of the sequence of characters that matched the regular expression 
m[0].matched  true 
m[n].first  
m[n].second  
m[n].matched  For all integers 0 < n < m.size(), true if subexpression n
participated in the match, false otherwise. 
Subclause  Header(s)  
Order and Consistency  
Lockfree Property  
Atomic Types  <atomic>  
Operations on Atomic Types  
Flag Type and Operations  
Fences 
key  Op  Computation  key  Op  Computation 
add  +  addition  sub    subtraction 
or    bitwise inclusive or  xor  ^  bitwise exclusive or 
and  &  bitwise and 
Subclause  Header(s)  
Requirements  
Threads  <thread>  
Mutual exclusion  <mutex>  
<shared_mutex>  
Condition variables  <condition_variable>  
Futures  <future> 
<assert.h>  <inttypes.h>  <signal.h>  <stdio.h>  <wchar.h> 
<complex.h>  <iso646.h>  <stdalign.h>  <stdlib.h>  <wctype.h> 
<ctype.h>  <limits.h>  <stdarg.h>  <string.h>  
<errno.h>  <locale.h>  <stdbool.h>  <tgmath.h>  
<fenv.h>  <math.h>  <stddef.h>  <time.h>  
<float.h>  <setjmp.h>  <stdint.h>  <uchar.h> 
Element  Value 
strmode  dynamic 
alsize  alsize_arg 
palloc  a null pointer 
pfree  a null pointer 
Element  Value 
strmode  dynamic 
alsize  an unspecified value 
palloc  palloc_arg 
pfree  pfree_arg 
Element  Value 
strmode  0 
alsize  an unspecified value 
palloc  a null pointer 
pfree  a null pointer 
Conditions  Result 
(which & ios::in) != 0  positions the input sequence 
(which & ios::out) != 0  positions the output sequence 
(which & (ios::in  ios::out)) == (ios::in  ios::out)) and way == either ios::beg or ios::end  positions both the input and the output sequences 
Otherwise  the positioning operation fails. 