std::bitset::operator[]

C++

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Language support library

Concepts library (C++20)

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Regular expressions library (C++11)

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Technical Specifications

Utilities library

Type support (basic types, RTTI, type traits)
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initializer_list (C++11)
bitset
hash (C++11)
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rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
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strong_order weak_order partial_order strong_equal weak_equal	strong_ordering weak_ordering partial_ordering strong_equality weak_equality	is_eqis_neqis_ltis_lteqis_gtis_gteq
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std::bitset

Member types

bitset::reference

Member functions

bitset::bitset

bitset::operator==bitset::operator!=

Element access

bitset::operator[]

bitset::test

bitset::allbitset::anybitset::none (C++11)

bitset::count

Capacity

bitset::size

Modifiers

bitset::operator&=bitset::operator|=bitset::operator^=bitset::operator~

bitset::operator<<=bitset::operator>>=bitset::operator<<bitset::operator>>

bitset::set

bitset::reset

bitset::flip

Conversions

bitset::to_string

bitset::to_ulong

bitset::to_ullong (C++11)

Non-member functions

operator&operator|operator^

operator<<operator>>

Helper classes

std::hash (C++11)

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

See also

test	accesses specific bit (public member function)