count_if

Interface

template<typename InputIterator, typename Predicate>
inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
count_if(InputIterator first, InputIterator last, Predicate pred);

Returns

The number of iterators i in the range [first,last) for which the following corresponding conditions hold: pred(*i).

Examples

#include <sprout/algorithm/count_if.hpp>
#include <sprout/array.hpp>
#include <sprout/container.hpp>
#include <sprout/functional.hpp>
using namespace sprout;

SPROUT_STATIC_CONSTEXPR auto input = array<int, 10>{{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}};
SPROUT_STATIC_CONSTEXPR auto result = sprout::count_if(begin(input), end(input), bind2nd(modulus<>(), 2));
static_assert(result == 5, "counted 5 elements of odd number from input.");

Complexity

Exactly last - first applications of the predicate.

Recursive function invocations in O(logN) (logarithmic) depth.

Header

sprout/algorithm/count_if.hpp

Convenience header: sprout/algorithm.hpp