Factorial using command line arguments:

#include<stdio.h>
#include<stdlib.h>
int main(int argc, char * argv[]) {
    int i, sum = 0;
long int fact=1;
    if (argc != 2)
    {
      exit(1);
    }
if(atoi(argv[1])==0||atoi(argv[1])==1)
fact=1;
else
  for (i = 2; i <=atoi(argv[1]); i++)
      fact=fact*i;
  printf("Factorial of %s is %ld\n", argv[1],fact);
return 0;
}