Write a C Program to find the Factorial of a number

/*
Summary: Factorial is represented using '!', so five factorial will be written as (5!),n factorial as (n!).
n! = n*(n-1)*(n-2)*(n-3)...3.2.1 and zero factorial is defined as one i.e. 0! = 1.
*/


/* Using While Loop */ 
#include<stdio.h>
void main()
{
    int a,f,i;
    printf("Enter a number: ");
    scanf("%d",&a);
    f=1;
    i=1;
    while(i<=a)
    {
        f = f * i;
        i++;
    }
    printf("Factorial: %d",f);
}


/* Using For Loop */ 
#include<stdio.h>
void main()
{
    int a,f,i;
    printf("Enter a number: ");
    scanf("%d",&a);
    f=1;
    for(i=1;i<=a;i++)
        f = f * i;
    printf("Factorial: %d",f);
}



/*Using Recursion */
#include<stdio.h>
int fact(int);
int main(){
 int num,f;

 printf("\nEnter a number: ");
 scanf("%d",&num);

 f=fact(num);

 printf("\nFactorial of %d is: %d",num,f);
 return 0;
}

//recursive function
int fact(int n){
 if(n==1)
  return 1;
 else
  return(n*fact(n-1));
}