Question

Construct two small C programs, compile and set up two executable files for the two commands world and mars. Both commands simply print out messages on the screen:

world n - print the message hello world on the screen n times

mars n - print the message HELLO MARS on the screen n times

Thanks a lot for your help!!!

Answer 1

world.c

#include <stdio.h> /*typically in /usr/include*/
#include <stdlib.h>

int main (int argc, char* argv [ ])
/*pass command line arguments from shell;
argc-number of parameters and argv[]—the arguments*/
{
   int count, i;
   if (argc != 2)
   {
      fprintf(stderr, "usage: %s count\n", argv[0]);
/* run as- hello world count*/
      exit (-1);
/*signal error (return other than 0) to shell*/
   }
   else
      count = atoi (argv[1]);

   for ( i = 0; i < count; i++ )
      printf("hello world!\n");

   return 0;
}

mars.c

#include <stdio.h> /*typically in /usr/include*/
#include <stdlib.h>

int main (int argc, char* argv [ ])
/*pass command line arguments from shell;
argc-numberof parameters and argv[]—the arguments*/
{
   int count, i;
   if (argc != 2)
   {
      fprintf(stderr, "usage: %s count\n", argv[0]);
/* run as- hello world count*/
      exit (-1);
/*signal error (return other than 0) to shell*/
   }
   else
      count = atoi (argv[1]);

   for ( i = 0; i < count; i++ )
      printf("Hello Mars!\n");

   return 0;
}