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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 ``#include ``#include ``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 ``#include ``#include ``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
```
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