The C++ Standard Library consists of the header, <algorithm> which defines a collection of functions (principally designed to deal with a range of elements). count() is a method in the STL that returns the number of elements in a range that are equal to a certain value.
Syntax:
count( iterator_begin, iterator_end, val);
Parameters: The count() method accepts 3 parameters
- iterator_begin: Iterator to the initial position
- iterator_end: Iterator to the final position ( Note: the range is [iterator_begin,iterator_end) )
- val: Value to match
Return value: Number of elements in the range equal to val
Example of count() method
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
v.push_back(3);
v.push_back(5);
v.push_back(3);
cout<<"Number of times 3 is repeated: "<< count(v.begin(), v.end(), 3) << endl;
}
Output:
Number of times 3 is repeated: 3
