NAME¶

std::bitset::operator[] - std::bitset::operator[]

Synopsis¶

bool operator[]( std::size_t pos ) const; (until C++11)
constexpr bool operator[]( std::size_t pos ) (since C++11)
const; (1)
reference operator[]( std::size_t pos ); (until C++23)
constexpr reference operator[]( std::size_t pos (2) (since C++23)
);

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{0b00101010}; // binary literal for 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

See also¶

test accesses specific bit
(public member function)