/**
 * command-line.c
 *   A simple example of command-line processing in C.  Reads various
 *   flags from the command line and prints out info on those flags.
 */

#include <stdio.h>

void
helper (FILE *fp)
{
  int ch;
  while ((ch = fgetc(fp)) != EOF)
    putc (ch, stdout);
} // helper

int
main (int argc, char *argv[])
{
  int i;
  int reverse = 0;      // Are we sorting in reverse mode?
  int numeric = 0;      // Are we sorting in numeric mode?
  int width = 256;      // The width of a line
  char *filename = NULL;// The name of the file we want to sort.
  FILE *fp;             // The file we're sorting.

  // Parse the command line
  for (i = 1; i < argc; i++)
    {
      if (strcmp (argv[i], "-r") == 0)
        reverse = 1;
      else if (strcmp (argv[i], "-n") == 0)
        numeric = 1;
      else
        filename = argv[i];
    }

  // Do something with the parsed command line info
  if (reverse)
    printf ("Reverse ");
  if (numeric)
    printf ("Numeric ");
  printf ("Sorting of ");
  if (filename)
    printf ("the file %s", filename);
  else
    printf ("stdin");
  printf ("\n");

  // Use the specified file, if given
  if (filename)
    fp = fopen (filename, "r");
  else
    fp = stdin;

  if (fp == NULL)
    {
      printf ("No such file: %s\n", filename);
      return 1;
    }

  // Do the real work
  helper (fp);

  // Clean up after ourselves
  if (filename)
    close (fp);

  // And we're done
  return 0;
} // main