std::bitset::test

 

C++

Language

Standard library headers

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Strings library

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Algorithms library

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Numerics library

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Regular expressions library (C++11)

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Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)

Dynamic memory management

Error handling

Program utilities

Variadic functions

Date and time

Function objects

initializer_list (C++11)

bitset

hash (C++11)

Relational operators

rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=

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pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

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swap

exchange (C++14)

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move (C++11)

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Type operations

declval (C++11)

as_const (C++17)

 

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)

 

bool test( size_t pos ) const;

Returns the value of the bit at the position pos.

Unlike operator[], performs a bounds check and throws std::out_of_range if pos does not correspond to a valid position in the bitset.

Parameters

pos

-

position of the bit to return

Return value

true if the requested bit is set, false otherwise.

Exceptions

std::out_of_range if pos does not correspond to a valid position within the bitset.

Example

Run this code

#include <iostream>
#include <bitset>
 
int main() 
{
    std::bitset<10> b1("1111010000");
 
    size_t idx = 0;
    while (idx < b1.size() && !b1.test(idx)) {
      ++idx;
    }
 
    if (idx < b1.size()) {
        std::cout << "first set bit at index " << idx << '\n';
    } else {
        std::cout << "no set bits\n";
    }
}

Output:

first set bit at index 4

See also

operator[]

accesses specific bit (public member function)