615: Highlights

• If you want to supply command-line arguments, then indicate that the main function is to have two parameters—one that holds a count of the space-separated command-line strings, and another that holds an array of pointers to those command-line strings:

  main (int argument_count, char **argument_array) {...} 
  

• If you want to include a command-line file name, which, by convention, should be the final command-line argument, then instantiate the following pattern:

  main (int argument_count, char **argument_array) { 
    ... 
    /* Declare a pointer to a file-describing structure */ 
    FILE* file-pointer name; 
    ... 
    /* Test argument count */ 
    if (argument_count < 2) { 
      printf ("Sorry, %s requires at least one argument.\n", 
                      argument_array [0]); 
      exit (0);} 
    /* Prepare a file-describing structure for reading */ 
    file-pointer name 
      = fopen (argument_array[argument_count - 1], "r"); 
    /* Make sure file opened properly */ 
    if (file-pointer name == NULL) { 
      printf ("Sorry, %s is not a file name.\n", 
                      argument_array [argument_count -1]); 
      exit (0);} 
    ... 
    statements that read information from the specified file 
  

• If you want to include command-line flags, which, by convention, should be marked with hyphens, as well as with a file name, then instantiate and supplement the following pattern for a single flag:

  main (int argument_count, char **argument_array) { 
    ... 
    /* Declare flag switches */ 
    int flag_switch = 0; 
    ... 
  // Set up file pointer 
   /* Analyze flags */ 
   for (argument_counter = 1; 
        argument_counter < argument_count - 1; 
        ++argument_counter) 
    if (argument_array [argument_counter][0] == '-')  
      for (string_counter = 1; 
           argument_array[argument_counter][string_counter]; 
           ++string_counter) 
        switch (argument_array [argument_counter][string_counter])  
         { 
          case 'flag character to be recognized':  
            flag_switch = 1; 
            break; 
          default:  
            printf ("%c is not a recognized flag.\n",  
               argument_array [argument_counter][string_counter]); 
            break; 
          }