public member function

std::bitset::test

bool test (size_t pos) const;

Return bit value

Returns whether the bit at position pos is set (i.e., whether it is one).

Unlike the access operator (operator[]), this function performs a range check on pos before retrieveing the bit value, throwing out_of_range if pos is equal or greater than the bitset size.

Parameters

pos: Order position of the bit whose value is retrieved.
Order positions are counted from the rightmost bit, which is order position 0.
size_t is an unsigned integral type.

Return value

true if the bit at position pos is set, and false if it is not set.

Example

// bitset::test
#include <iostream>       // std::cout
#include <string>         // std::string
#include <cstddef>        // std::size_t
#include <bitset>         // std::bitset

int main ()
{
  std::bitset<5> foo (std::string("01011"));

  std::cout << "foo contains:\n";
  std::cout << std::boolalpha;
  for (std::size_t i=0; i<foo.size(); ++i)
    std::cout << foo.test(i) << '\n';

  return 0;
}

Output:


foo contains:
true
true
false
true
false

Data races

The bitset is accessed.

Exception safety

Strong guarantee: if an exception is thrown, there are no changes in the bitset.
If pos is not a valid bit position, out_of_range is thrown.