std::bitset<N>::flip

bitset& flip();	(1)	(noexcept since C++11) (constexpr since C++23)
bitset& flip( std::size_t pos );	(2)	(constexpr since C++23)

Flips bits, i.e. changes true values to false and false values to true. Equivalent to a logical NOT operation on part or all of the bitset.

1) Flips all bits (like operator~, but in-place).

2) Flips the bit at the position pos.

Parameters

pos

the position of the bit to flip

Return value

*this

Exceptions

2) Throws std::out_of_range if pos does not correspond to a valid bit position.

Example

#include <bitset>
#include <iostream>

int main()
{
    std::bitset<4> flops;
    
    std::cout << flops << '\n'
              << flops.flip(0) << '\n'
              << flops.flip(2) << '\n'
              << flops.flip() << '\n';
}

Output:

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2250	C++98	the behavior was undefined if `pos` does not correspond to a valid bit position	always throws an exception in this case