std::bitset<N>::operator[]
From cppreference.com
bool operator[]( std::size_t pos ) const; |
(1) | (constexpr since C++11) |
reference operator[]( std::size_t pos ); |
(2) | (constexpr since C++23) |
Accesses the bit at position pos.
1) Returns the value of the bit.
2) Returns an object of type std::bitset::reference that allows modification of the value.
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If pos < size() is false, the behavior is undefined. |
(until C++26) |
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If pos < size() is false:
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(since C++26) |
Contents |
[edit] Parameters
| pos | - | position of the bit to return |
[edit] Return value
1) The value of the requested bit.
2) An object of type std::bitset::reference, which allows writing to the requested bit.
[edit] Exceptions
Throws nothing.
[edit] Example
Run this code
#include <bitset> #include <cstddef> #include <iostream> 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, b1 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, b1 holds 00101011
[edit] 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 11 | C++98 | 1. the description was missing in the C++ standard 2. there was only the non-const overload |
1. description added 2. added the const overload |
| LWG 907 | C++98 | the behavior of reading the bit at pos was equivalent to that of test(pos), but test() may throw exceptions
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avoids mentioning test()
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[edit] See also
| accesses specific bit (public member function) |
