text: #include <stdio.h>
  
  /*
  * This the program entry function. The parameters provide a means to access the
  * command line arguments.
  * argc - The number of command line arguments
  * argv - A pointer to the first argument (text string)
  */
  int main (int argc, char* argv[]) {
  
    switch (argc) {
      // In case of no extra arguments
      case 1:
        printf("Hello world!\n");
        break;
  
      // In case of one argument
      case 2:
        printf("Hello %s!\n", argv[1]);
        break;
  
      // Else
      default: 
        printf("Wrong usage\n");
        break;
    }
  
    return 0;
  
  }
  