> On June 20, 2016 at 10:37 AM Edward Bartolo <edbarx@???> wrote:
>
> On page Page 34 Exercise 1-9
> "Write a program to copy its input to its output, replacing each
> string of blanks one ore more blanks by a single blank."
>
> I wrote the following, tested it, and it seems to work, but I think it is
> too complicated. Any suggestions?

Here's another way to do it:

  /*
   * K&R exercise
   *
   * Replace multiple blanks with single blank    
   */

#include <stdio.h>
#include <string.h>
#include <errno.h>

  static
  int
  filter (void)
  {
    int ch = getchar ();    /* all the logic is here */
    if (EOF != ch)
      {
        putchar (ch);
        if (' ' == ch)
          for (;;)
            {
              ch = getchar ();
              if (' ' != ch)
                {
                  if (EOF != ch)
                    putchar (ch);
                  break;
                }
            }
      }
    return ch;
  }

  static
  int
  checkError (FILE * fp, const char *arg)
  {
    if (ferror (fp))
      {
        const char *pgmName = strrchr (arg, '/');
        if (pgmName)
          pgmName++;    /* get beyond the slash */
        else
          pgmName = arg;
        fprintf (stderr, "%s: I/O error: %s\n", pgmName, strerror (errno));
        return 1;
      }
    return 0;
  }

  int
  main (int argc, char **argv)
  {
    while (EOF != filter ())
      continue;           /* this version encodes state in program structure */
    if (checkError (stdin, argv[0]))
      return 1;        /* this version checks for errors */
    if (checkError (stdout, argv[0]))
      return 1;         /* I didn't actually reproduce this error, it is hard to test */
    return 0;
  }

I hope this survives line wrapping :-)

Peter Olson