Recursion is a process in which a function calls itself. In a programming language, if a program allows calling of a function inside the same function, then the function is termed as recursive function and this process of calling itself is called Recursion.
There are two main requirements for a function to be recursive:
1. Terminating condition - the function must return when the terminating condition is satisfied.
2. Recursive call - the function must call itself.
Example:-
int fun()
{
...
...
fun();
...
...
}
Here we can see that, the function fun( ) calls itself.
C program:-
#include <stdio.h>
int fun(int
n)
{
if (n == 0)
return 0;
else
return fun(n - 1) + n;
}
int main()
{
int sum = 0, x;
printf("number");
scanf("%d", &x);
sum = fun(x);
printf("%d\n", sum);
return 0;
}