Count the number of occurrences of a particular value in a range of elements.
On line 7, we create a std::vector of int initialized with some values.
On lines 9–11, we use the alrogithm std::count, to count the occurrences of a particular value in the std::vector. For the first two arguments on lines 9–10, we use std::begin and std::end to get the begin and end iterators for the range in which we wish to count. The third argument on line 11 is the value to count the occurrences of.
To count elements according to a predicate, you can use std::count_if instead.