std::count_if is an STL algorithm for counting elements in a container matching a certain predicate. For counting without a predicate use std::count.
Example: CountNonZeroes
#include <algorithm> #include <vector> //From http://www.richelbilderbeek.nl/CppCountNonZeroes.htm int CountNonZeroes(const std::vector<double>& v) { return std::count_if( v.begin(), v.end(), std::bind2nd(std::not_equal_to<double>(),0.0)); }