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Q67354: putch() Displays Values 9 and 255 Differently in DOS and OS/2

Article: Q67354
Product(s): See article
Version(s): 6.00 6.00a | 6.00 6.00a
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | buglist6.00 buglist6.00a | mspl13_c
Last Modified: 4-DEC-1990

The putch() function will display different output for the values 9
(tab) and 255 depending on whether you are running in DOS or OS/2.
When passing a tab (ASCII 9) to putch() under DOS, the graphic ASCII
character for 9 is displayed. Under OS/2, a tab is expanded out to
actual spaces when passed to putch().

When passing the value 255 to putch() under DOS, the value is ignored
and nothing is displayed. Passing 255 to putch() under OS/2 results in
a space being displayed.

Because the cprintf() function uses putch() to display characters, the
same differences will appear with these values when calling cprintf().

Microsoft has confirmed this to be a problem in C versions 6.00 and
6.00a. We are researching this problem and will post new information
here as it becomes available.

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