Example to find the GCD of two positive integers (entered by the user) using recursion in C programming.

To understand this example, you should have the knowledge of following C++ programming topics:

This program takes two positive integers from user and calculates GCD using recursion.

Visit this page to learn, how you can calculate GCD using loops.

```
#include <iostream>
using namespace std;
int hcf(int n1, int n2);
int main()
{
int n1, n2;
cout << "Enter two positive integers: ";
cin >> n1 >> n2;
cout << "H.C.F of " << n1 << " & " << n2 << " is: " << hcf(n1, n2);
return 0;
}
int hcf(int n1, int n2)
{
if (n2 != 0)
return hcf(n2, n1 % n2);
else
return n1;
}
```

**Output**

Enter two positive integers: 366 60 H.C.F of 366 and 60 is: 6