template<class InputIterator, class T>
typename iterator_traits<InputIterator>::difference_type
count(InputIterator first, InputIterator last, const T& value);
template<class ExecutionPolicy, class ForwardIterator, class T>
typename iterator_traits<ForwardIterator>::difference_type
count(ExecutionPolicy&& exec, ForwardIterator first, ForwardIterator last, const T& value);
template<class InputIterator, class Predicate>
typename iterator_traits<InputIterator>::difference_type
count_if(InputIterator first, InputIterator last, Predicate pred);
template<class ExecutionPolicy, class ForwardIterator, class Predicate>
typename iterator_traits<ForwardIterator>::difference_type
count_if(ExecutionPolicy&& exec, ForwardIterator first, ForwardIterator last, Predicate pred);
Effects:
Returns the number of iterators
i
in the range
[first, last)
for which the following corresponding
conditions hold:
*i == value, pred(*i) != false. Complexity:
Exactly
last - first
applications of the corresponding predicate
.