Recursive Function in C programming language

Question

Explain concept of recursive function using example to find factorial of given positive integer

Answer 1

Recursive Function is a function which calls itself.

To solve a problem recrusively, there are TWO conditions

which must be met:

(1) Stopping case: no recursion occurs, which ends the

chain of recrusive calls made to the function

(2) Recursive case: The main part of the problem

where the recursive calls are made

The example of factorials:

For NON-Negative integer N:

N! = N * (N-1)! if N>1

1 if N>=0

So for example 5! = 5 * 4!

= 5 * 4 * 3!

= 5 * 4 * 3 * 2!

= 5 * 4 * 3 * 2 * 1!

= 5 * 4 * 3 * 2 * 1

= 120

/*******************************************/

#include <stdio.h>

long factorial( long N)

{

long returnVal=-1;

if (N>1) //N=2,3,4,....

{

returnVal = N * factorial(N-1); //recursive call

}

else //invalid input parameter N must be non-negative

{

returnVal=1; //0! = 1! = 1

}

return(returnVal);

}

int main()

{

printf("%ld",factorial(5));

}