Question

C program to find factorial of the given number.

Answer 1

Program: To calculate the factorial value using recursion.

#include <stdio.h>
int fact(int n);
int main()
{
 int x, i;
 printf("Enter a value for x: \n");
 scanf("%d", &x);
 i = fact(x);
 printf("\nFactorial of %d is %d", x, i);
 return 0;
}

int fact(int n) {
 /* n=0 indicates a terminating condition */
 if (n <= 0)
{
  return (1);
 } else
{
  /* function calling itself */
  return (n * fact(n - 1));
  /*n*fact(n-1) is a recursive expression */
 }
}

Output:
Enter a value for x:
4
Factorial of 4 is 24


Explanation:
  fact(n) = n * fact(n-1)
  If n=4
  fact(4) = 4 * fact(3)  there is a call to fact(3)
  fact(3) = 3 * fact(2)
  fact(2) = 2 * fact(1)
  fact(1) = 1 * fact(0)
  fact(0) = 1
  fact(1) = 1 * 1 = 1
  fact(2) = 2 * 1 = 2
  fact(3) = 3 * 2 = 6
  Thus fact(4) = 4 * 6 = 24
Terminating condition(n <= 0 here;) is a must for a recursive program. Otherwise the program enters into an infinite loop.

Answer 2

#include<stdio.h>
void main()
{
int n,fact;
int factorial();
printf("enter the no'r whose factorial to be found");
scanf("%d",&n);
fact=factorial(n);
printf("factorial of the no'r=%d",fact);
}
int factorial(int x)
{
int i,f=1;
for(i=1;i<=x;i++)
{
f=f*i;
}
return(f);
}

Comments

it is the simplest format

Answer 3

 

#include<stdio.h>

main()

{

int a,i;

long int fact;

printf("\n Enter the value of a :");

scanf("%d",&a);

fact=1;

i=1;

while(i<=a)

{

fact=fact*i;

  i=i+1;

  }

printf("\nFactorial= %d",fact);

}