operator==(std::counted_iterator<I>, std::default_sentinel_t)

friend constexpr bool operator==(
  const counted_iterator& x, std::default_sentinel_t );
(since C++20)

Checks if the underlying length (i.e. distance to the end) is equal to ​0​.

This function template is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::counted_iterator<I> is an associated class of the arguments.

The != operator is synthesized from operator==.


x - an iterator adaptor

Return value

true if x.count() is equal to ​0​, false otherwise.


#include <initializer_list>
#include <iterator>
int main()
    static constexpr auto v = {1, 2, 3, 4};
    constexpr std::counted_iterator<std::initializer_list<int>::iterator>
        it1 {v.begin(), 3},
        it2 {v.begin(), 0};
    static_assert( it1 != std::default_sentinel );
    static_assert( it2 == std::default_sentinel );
    static_assert( std::default_sentinel != it1 );
    static_assert( std::default_sentinel == it2 );

See also

compares the distances to the end
(function template)

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