std::bitset::test

 

C++

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std::bitset

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

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bitset::all bitset::any bitset::none (C++11)

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

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bitset::to_ulong

bitset::to_ullong (C++11)

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operator& operator| operator^

operator<< operator>>

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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 << "lowest 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)