A function call itself in its body is called recursive function. A recursive function can be used instead of a loop control.  Hence, programmer should take care to avoid infinite loop.

/*program to find factorial of a number-without recursion*/

#include

main ()

{

int n, factorial;  //declaration of variables

int fact(int);      //declaration of fact function

printf (“Enter any number:\n” );

scanf (“%d”, &n);

factorial = fact (n);

printf (“Factorial is %d\n”, factorial);

}

/* Non recursive function of factorial */

int fact (int n)    //formal argument

{

int res = 1, i;

for (i = n; i >= 1; i–)

res = res * i;

return (res);

}

/*Program to find factorial using recursion*/

#include

main()

{

int n, factorial;

int fact(int);

printf(“Enter any number: \n” );

scanf(“%d”,&n);

factorial = fact(n); /*Function call */

printf (“Factorial is %d\n”, factorial); }

/* Recursive function of factorial */

int fact(int n)

{

int res;

if(n == 1) /* Terminating condition */

return(1);

else

res = n*fact(n-1); /* Recursive call */

return(res); }