#include <algorithm>
  size_t count( iterator start, iterator end, const TYPE& val );

The count() function returns the number of elements between start and end that match val.

For example, the following code uses count() to determine how many integers in a vector match a target value:

 vector<int> v;
 for( int i = 0; i < 10; i++ ) {
   v.push_back( i );
 }              

 int target_value = 3;
 int num_items = count( v.begin(), v.end(), target_value );             

 cout << "v contains " << num_items << " items matching " << target_value << endl;            

The above code displays the following output:

 v contains 1 items matching 3