# C++ Algorithm Library - for_each() Function

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## Description

The C++ function std::algorithm::for_each() applies provided function on each element of the range.

## Declaration

Following is the declaration for std::algorithm::for_each() function form std::algorithm header.

### C++98

```template <class InputIterator, class Function>
Function for_each (InputIterator first, InputIterator last, Function fn);
```

## Parameters

• first − Input iterator to the initial position.

• last − Final iterator to the final position.

• fn − Unary function that accepts an element in the range as argument.

## Return value

Returns function fn.

Linear.

## Time complexity

Throws exception if either function fn or an operation on an iterator throws exception.

Please note that invalid parameters cause undefined behavior.

## Example

The following example shows the usage of std::algorithm::for_each() function.

```#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int print_even(int n) {
if (n % 2 == 0)
cout << n << ' ';
}

int main(void) {
vector<int> v = {1, 2, 3, 4, 5};

cout << "Vector contains following even numebr" << endl;

for_each(v.begin(), v.end(), print_even);

cout << endl;

return 0;
}
```

Let us compile and run the above program, this will produce the following result −

```Vector contains following even numebr
2 4
```
algorithm.htm