Trouble at EOF

[Robert Osborne]

In article <4739 at inews.intel.com>, bhoughto at pima.intel.com (Blair P. Houghton) writes:
> Yes, fgets at eof may get a line with no newline.
> 
> Hence:
> 
>     while ( fgets(s, sizeof s, stream) )
>         /* not eof */
>         process(s);

Well you really want...
    if( fgets(s, sizeof s, stream) ) {
		do {
			process(s);
		} while ( fgets(s, sizeof s, stream) );
	}
or something similar.

>     /* reached iff eof */
>     if ( strlen(s) != 0 ) {
>         /* there's something left to process */
>         if ( s[strlen(s) - 1] != '\n' )
>             /* it has no newline */
>             strcat(s,"\n");
>         process(s);
>     }

This has two str??? calls too many...

    /* reached iff eof */
    if ( (s_length = strlen(s)) != 0 ) {
        /* there's something left to process */
        if ( s[s_length - 1] != '\n' ) {
            /* it has no newline */
        	s[s_length] = '\n';
        	s[s_length + 1] = '\0';
		}
        process(s);
    }

The str??? calls are OFTEN used in this manner and this is a very
common optimization that can be made in string handlers.
I once cut the running time of a key piece of UI functionality from
an intolerable >10 seconds to an almost bearable <5 seconds by performing
this kind of "optimization".

> But notice also that the size of the gotten string is
> limited to the number of chars specified in the second
> argument to fgets.

And this would be intolerable in a parser.  I'm surprised Blair didn't
mention this (although he did solve the problem asked).

Rob.
-- 
Robert A. Osborne   ...uunet!utai!lsuc!isgtec!robert or robert at isgtec.uucp