23 General utilities library [utilities]

23.9 Bitsets [bitset]

23.9.2 Class template bitset [template.bitset]

23.9.2.1 bitset constructors [bitset.cons]

constexpr bitset() noexcept;

Effects: Constructs an object of class bitset<N>, initializing all bits to zero.

constexpr bitset(unsigned long long val) noexcept;

Effects: Constructs an object of class bitset<N>, initializing the first M bit positions to the corresponding bit values in val. M is the smaller of N and the number of bits in the value representation of unsigned long long. If M < N, the remaining bit positions are initialized to zero.

template <class charT, class traits, class Allocator> explicit bitset( const basic_string<charT, traits, Allocator>& str, typename basic_string<charT, traits, Allocator>::size_type pos = 0, typename basic_string<charT, traits, Allocator>::size_type n = basic_string<charT, traits, Allocator>::npos, charT zero = charT('0'), charT one = charT('1'));

Throws: out_­of_­range if pos > str.size() or invalid_­argument if an invalid character is found (see below).

Effects: Determines the effective length rlen of the initializing string as the smaller of n and str.size() - pos.

The function then throws invalid_­argument if any of the rlen characters in str beginning at position pos is other than zero or one. The function uses traits​::​eq() to compare the character values.

Otherwise, the function constructs an object of class bitset<N>, initializing the first M bit positions to values determined from the corresponding characters in the string str. M is the smaller of N and rlen.

An element of the constructed object has value zero if the corresponding character in str, beginning at position pos, is zero. Otherwise, the element has the value one. Character position pos + M - 1 corresponds to bit position zero. Subsequent decreasing character positions correspond to increasing bit positions.

If M < N, remaining bit positions are initialized to zero.

template <class charT> explicit bitset( const charT* str, typename basic_string<charT>::size_type n = basic_string<charT>::npos, charT zero = charT('0'), charT one = charT('1'));

Effects: Constructs an object of class bitset<N> as if by:

bitset(n == basic_string<charT>::npos
          ? basic_string<charT>(str)
          : basic_string<charT>(str, n),
       0, n, zero, one)