Factorial Of A Number in C

Write A Program to Find Factorial Of A Number

Problem Can Be Solved Using 

1. Recursion

#include<stdio.h>
int fact(int num){
 if((num == 0)||(num == 1))
  return 1;
 else
  return num*fact(num-1);
}
int main(int argc, char *argv[]){
 int num;
 num = atoi(argv[1]);
 printf("%d!=%d\n",num,fact(num));
 return 0;
}

Compiling and Running Under Linux

rajesh@ThinkPad:~/Rajesh/blogs$ gcc factorial.c -o factnum
rajesh@ThinkPad:~/Rajesh/blogs$ ./factnum 4
4!=24
rajesh@ThinkPad:~/Rajesh/blogs$ ./factnum 5
5!=120
rajesh@ThinkPad:~/Rajesh/blogs$ ./factnum 6
6!=720

2. Using Loop

#include<stdio.h> 
int fact(int num){
 int res;
 res=1;
 while(num){
  res*=num;
  num--;
 }
 return res;
} 
int main(int argc, char *argv[]){
 int num;
 num = atoi(argv[1]);
 printf("%d!=%d\n",num,fact(num));
 return 0;
} 

Compiling and Running Under Linux

rajesh@ThinkPad:~/Rajesh/blogs$ gcc factorial.c -o factnum
rajesh@ThinkPad:~/Rajesh/blogs$ ./factnum 4
4!=24
rajesh@ThinkPad:~/Rajesh/blogs$ ./factnum 5
5!=120
rajesh@ThinkPad:~/Rajesh/blogs$ ./factnum 6
6!=720