Factorial

       Factorial system in c: c value to discover and list factorial of a variety, three techniques are given, first one uses a for cycle, second uses a operate to discover factorial and third using recursion. Factorial is showed using !, so five factorial will be published as 5!, n factorial as n!. Also
n! = n*(n-1)*(n-2)*(n-3)...3.2.1 and zero factorial is determined as one i.e. 0!=1.


#include<stdio.h>
#include<conio.h>

void main()
{
   int c, n, fact = 1;

   printf("Enter a number to calculate it's factorial\n");
   scanf("%d",&n);

   for( c = 1 ; c <= n ; c++ )
         fact = fact*c;

   printf("Factorial of %d = %d\n",n,fact);

   getch();
 
}

output :-
              Enter a number to it's factorial=6
              Factorial of 6=720

Factorial program in c using function :-

#include<stdio.h>
#include<conio.h>

long factorial(int);

void main()
{
   int number;
   long fact = 1;

   printf("Enter a number to calculate it's factorial\n");
   scanf("%d",&number);

   printf("%d! = %ld\n",number, factorial(number));

   getch();
}

long factorial(int n)
{
   int c;
   long result = 1;

   for( c = 1 ; c <= n ; c++ )
         result= result*c;

   return(result);
}

Factorial program in c using recursion :-

#include<stdio.h>
 #inculde<conio.h>

long factorial(int);

void main()
{
   int num;
   long f;

   printf("ENTER A NUMBER TO FIND FACTORIAL :");
   scanf("%d",&num);

   if(num<0)
      printf("NEGATIVE NUMBERS ARE NOT ALLOWED");
   else
   {
      f = factorial(num);
      printf("%d!=%ld",num,f);
   }
   return(0);
}

long factorial(int n)
{
   if(n==0)
      return(1);
   else
      return(n*factorial(n-1));
}