Std::bitset::operator&=,|=,^=,~ (3) Linux Manual Page

std::bitset<N>::operator[] – std::bitset<N>::operator[]

Synopsis

bool operator[]( std::size_t pos ) const; (until C++11)
constexpr bool operator[]( std::size_t pos ) const; (1) (since C++11)
reference operator[]( std::size_t pos ); (2)
Accesses the bit at position pos. The first version returns the value of the bit, the second version returns an object of type std::bitset::reference that allows modification of the value.
Unlike test(), does not throw exceptions: the behavior is undefined if pos is out of bounds.

Parameters

pos – position of the bit to return

Return value

1) the value of the requested bit
2) an object of type std::bitset::reference, which allows writing to the requested bit.

Exceptions

None

Example

// Run this code

#include <iostream>

#include <bitset>
int main()

{
    std::bitset<8> b1(42);
    for (std::size_t i = 0; i < b1.size(); ++i) {
        std::cout << "b1[" << i << "]: " << b1[i] << '\n';
    }
    b1[0] = true; // modifies the first bit through bitset::reference
    std::cout << "After setting bit 0, the bitset holds " << b1 << '\n';
}

Output:

  b1[0]: 0
  b1[1]: 1
  b1[2]: 0
  b1[3]: 1
  b1[4]: 0
  b1[5]: 1
  b1[6]: 0
  b1[7]: 0
  After setting bit 0, the bitset holds 00101011

std::bitset::operator&=,|=,^=,~ (3) Linux Manual Page