Skip to content
Related Articles

Related Articles

Count elements in a vector that match a target value or condition
  • Last Updated : 11 Nov, 2018

To determine number of integers in a vector that matches a particular value.

We use count in C++ STL




// CPP program to count vector elements that
// match given target value.
#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
  
int main()
{
    vector<int> v{ 10, 30, 30, 10, 30, 30 };
    int target = 30;
    int res = count(v.begin(), v.end(), target);
    cout << "Target: " << target << " Count : " << res << endl;
    return 0;
}
Output:
Target: 30 Count : 4

How to count elements matching a condition?
We can use lambda expressions in C++ to achieve this.

We use count_if in C++ STL




// lambda expression to count elements
// divisible by 3.
#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
int main()
{
    vector<int> v{ 10, 18, 30, 10, 12, 45 };
    int res = count_if(v.begin(), v.end(),
                       [](int i) { return i % 3 == 0; });
    cout << "Numbers divisible by 3: " << res << '\n';
    return 0;
}
Output:
Numbers divisible by 3: 4
Want to learn from the best curated videos and practice problems, check out the C++ Foundation Course for Basic to Advanced C++ and C++ STL Course for foundation plus STL.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.



My Personal Notes arrow_drop_up
Recommended Articles
Page :