std::distance

 

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input_iterator_tag output_iterator_tag forward_iterator_tag bidirectional_iterator_tag random_access_iterator_tag
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Defined in header <iterator>
template< class InputIterator > typename std::iterator_traits<InputIterator>::difference_type     distance( InputIterator first, InputIterator last );

Returns the number of elements between first and last.

If InputIterator is a random access iterator last - first is returned.

If InputIterator is a input, forward or bidirectional iterator the number of increment operations to get from first to last is returned.

Parameters

first	-	Iterator pointing to the first element. If InputIterator is a random access iterator last shall be reachable from first or first shall be reachable from last.
last	-	Iterator pointing to the last element. If InputIterator is a random access iterator last shall be reachable from first or first shall be reachable from last. If is a input, forward or bidirectional iterator last shall be reachable from first.

Return value

The number of elements between first and last.

Example

#include <iostream>
#include <iterator>
#include <vector>
 
int main() 
{
    std::vector<int> v{ 3, 1, 4 };
 
    auto distance = std::distance(v.begin(), v.end());
 
    std::cout << distance << '\n';
}

Output:

3

See also

advance	advances an iterator by given distance (function)