30 Input/output library [input.output]

30.7 Formatting and manipulators [iostream.format]

30.7.8 Quoted manipulators [quoted.manip]

[Note
:
Quoted manipulators provide string insertion and extraction of quoted strings (for example, XML and CSV formats).
Quoted manipulators are useful in ensuring that the content of a string with embedded spaces remains unchanged if inserted and then extracted via stream I/O.
end note
]
template <class charT> unspecified quoted(const charT* s, charT delim = charT('"'), charT escape = charT('\\')); template <class charT, class traits, class Allocator> unspecified quoted(const basic_string<charT, traits, Allocator>& s, charT delim = charT('"'), charT escape = charT('\\')); template <class charT, class traits> unspecified quoted(basic_string_view<charT, traits> s, charT delim = charT('"'), charT escape = charT('\\'));
Returns: An object of unspecified type such that if out is an instance of basic_­ostream with member type char_­type the same as charT and with member type traits_­type, which in the second and third forms is the same as traits, then the expression out << quoted(s, delim, escape) behaves as a formatted output function of out.
This forms a character sequence seq, initially consisting of the following elements:
  • delim.
  • Each character in s.
    If the character to be output is equal to escape or delim, as determined by traits_­type​::​eq, first output escape.
  • delim.
Let x be the number of elements initially in seq.
Then padding is determined for seq as described in [ostream.formatted.reqmts], seq is inserted as if by calling out.rdbuf()->sputn(seq, n), where n is the larger of out.width() and x, and out.width(0) is called.
The expression out << quoted(s, delim, escape) shall have type basic_­ostream<charT, traits>& and value out.
template <class charT, class traits, class Allocator> unspecified quoted(basic_string<charT, traits, Allocator>& s, charT delim = charT('"'), charT escape = charT('\\'));
Returns: An object of unspecified type such that:
  • If in is an instance of basic_­istream with member types char_­type and traits_­type the same as charT and traits, respectively, then the expression in >> quoted(s, delim, escape) behaves as if it extracts the following characters from in using operator>>(basic_­istream<charT, traits>&, charT&) ([istream.extractors]) which may throw ios_­base​::​failure ([ios::failure]):
    • If the first character extracted is equal to delim, as determined by traits_­type​::​eq, then:
      • Turn off the skipws flag.
      • s.clear()
      • Until an unescaped delim character is reached or !in, extract characters from in and append them to s, except that if an escape is reached, ignore it and append the next character to s.
      • Discard the final delim character.
      • Restore the skipws flag to its original value.
    • Otherwise, in >> s.
  • If out is an instance of basic_­ostream with member types char_­type and traits_­type the same as charT and traits, respectively, then the expression out << quoted(s, delim, escape) behaves as specified for the const basic_­string<charT, traits, Allocator>& overload of the quoted function.
The expression in >> quoted(s, delim, escape) shall have type basic_­istream<charT, traits>& and value in.
The expression out << quoted(s, delim, escape) shall have type basic_­ostream​<charT, traits>& and value out.