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Q68911: Sample Program SAMPLER.C Does Not Work Correctly

Article: Q68911
Product(s): See article
Version(s): 2.50 2.51
Operating System(s): MS-DOS
Keyword(s): ENDUSER | docerr s_c | mspl13_c
Last Modified: 1-FEB-1991

The sample program SAMPLER.C, included in the Microsoft QuickC "C for
Yourself" manual that shipped with QuickC version 2.50, is incorrect
and will always exit with the following message:

   Error:  can't set font

The correction listed below is also documented in the README.DOC
shipped with QuickC version 2.50.

The problem is on line 58 of SAMPLER.C, where the return value for the
_setfont() function is checked. The sample program uses the logical
not operator "!" to determine if an error code was returned. The
problem with this method is that _setfont() returns a negative number
to signify an error, or the font index number, if successful. Previous
implementations of _setfont() returned 0 (zero) if successful, or -1
if unsuccessful. The online help for C version 6.00 still documents
the old return values, as noted in the README.DOC shipped with C
version 6.00:

   The return values for _setfont as described in on-line help are
   incorrect. The _setfont function returns the font index number if
   successful, or a negative number if unsuccessful.

The same error exists in the Microsoft Press book "Microsoft C
Run-Time Library Reference" for C version 6.00. However, the return
values for _setfont() are documented correctly in the online help for
QuickC version 2.50.

To correct the problem, change line 58 from

   if(!_setfont( list ))

to the following:

   if( _setfont( list ) >= 0 )

As stated above, this correction is noted in the README.DOC that
shipped with QuickC version 2.50.

Also note that the return value of _setfont() (as documented above) is
valid only for C versions 6.00 and 6.00a and QuickC versions 2.50 and
2.51. The _setfont() function in the libraries shipped with QuickC
versions 2.00 and 2.01 (as well as C version 5.10) use the previous
implementations' return codes; therefore, the program will run
correctly when compiled using those versions.

The program SAMPLER.C can be found on page 302 of the "C for Yourself"
manual. It can also be found in the QuickC online help by selecting
the Help menu, choosing Contents, choosing "C for Yourself Sample
Programs", and finally, choosing SAMPLER.C.

The correct version of SAMPLER.C can be found on page 242 of the
"Microsoft C Advanced Programming Techniques" manual that shipped with
C versions 6.00 and 6.00a.

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