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Re: program which removes comments from C source

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On 2011-06-14, Ceriousmall <divadsmall@gmail.com> wrote:
> int gotline(char line[], int max)
> {
> 	int c, length;
>
> 	for (length = 0; length < max-2 && (c = getchar()) != EOF && c !=
> '\n'; ++length)
> 		line[length] = c;
>
> 	if (c == '\n')
> 		line[length++] = c;
>
> 	line[length] = '\0';
>
> 	if (c == EOF)
> 		return c;
> }

The gotline() function does not always return a value.
What is the purpose of the ``if (c == EOF)'' test?

> [snip]

> int main(void)
> {
> 	char line[MAXLINE+1];
> 	int at_start, at_end, return_val;
>
> 	at_start = cmt_state = qts_state = OUT;
>
> 	while (at_start != EOF) {
> 		return_val = gotline(line, MAXLINE);
> 		at_end = return_val == EOF;
> 		delcom(line, IN, OUT);
> 		printf("%s", line);
>
> 		if (at_end)
> 			at_start = return_val;
> 	}
> 	return 0;
> }

The last element of line[] is never used; it could be declared as
line[MAXLINE];
at_end and return_val are redundant; the following does the same thing:

  int main(void)
  {
  	char line[MAXLINE+1];
  	int at_start;
 
  	at_start = cmt_state = qts_state = OUT;
 
  	while (at_start != EOF) {
  		at_start = gotline(line, MAXLINE);
  		delcom(line, IN, OUT);
  		printf("%s", line);
  	}
  	return 0;
  }

The program does not perform well if there are lines longer than MAXLINE
(you can verify this by setting MAXLINE to a small value, e.g. 32, and
let the program process itself as input).

Why do you process the input line-by-line anyway? The program only needs
to buffer a few (probably two) characters, not an entire line; comment
text can be replaced by spaces on-the-fly, no need to postpone this
until end-of-line or end-of-comment is seen.
The line handling makes the program more complicated than necessary.

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program which removes comments from C source Ceriousmall <divadsmall@gmail.com> - 2011-06-13 18:20 -0700
  Re: program which removes comments from C source Ceriousmall <divadsmall@gmail.com> - 2011-06-13 18:23 -0700
  Re: program which removes comments from C source Keith Thompson <kst-u@mib.org> - 2011-06-13 19:23 -0700
  Re: program which removes comments from C source Ceriousmall <divadsmall@gmail.com> - 2011-06-13 19:37 -0700
    Re: program which removes comments from C source Ceriousmall <divadsmall@gmail.com> - 2011-06-13 19:41 -0700
    Re: program which removes comments from C source Ian Collins <ian-news@hotmail.com> - 2011-06-14 14:57 +1200
  Re: program which removes comments from C source Ceriousmall <divadsmall@gmail.com> - 2011-06-13 19:53 -0700
    Re: program which removes comments from C source Ike Naar <ike@iceland.freeshell.org> - 2011-06-14 07:23 +0000
      Re: program which removes comments from C source Ceriousmall <divadsmall@gmail.com> - 2011-06-14 14:15 -0700
  Re: program which removes comments from C source Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-14 16:30 -0700

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