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

ID Number: Q67354

6.00 6.00a 6.00ax | 6.00 6.00a

MS-DOS | OS/2

buglist6.00 buglist6.00a buglist6.00ax

Summary:

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 6.0, 6.0a,

and 6.0ax. We are researching this problem and will post new

information here as it becomes available.