////////    FIle factorial.C    ///////
#include <iostream.h>
#include <stdlib.h>  // for atoi

int factorial(int n)
{ int ans = 1;
      while (n > 1)
      {    ans = ans * n;       
           n = n - 1;
      } 
      return(ans);
}


int main(int argc, char *argv[])
{ int j;
      if (argc != 2)
      {    cout << "factorial takes one integer argument\n";
           return(1);     // abnormal termination of main
      }
      j = atoi(argv[1]);  // ASCII string to int conversion
      cout <<  "factorial(" << j << ")= "
           << factorial(j) << "\n";
      return(0);
}