To find the hcf between two numbers using recursion function

In this program I have given the concept of finding the hcf between two numbers using function.
The highest common factor of integers x and y is the largest integer that evenly divides both x and y.
The main points to be remember while doing this program is:

If y is equal to 0, then hcf(x,y) is x,
otherwise
hcf(x,y) is hcf(y,x%y)
 The main source code of the program is given below: