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Q50339: Not All Extended ASCII Characters Are Mapped by QuickC Fonts

Article: Q50339
Product(s): See article
Version(s): 2.00
Operating System(s): MS-DOS
Keyword(s): ENDUSER | S_QuickASM | mspl13_c
Last Modified: 17-JUL-1990

Problem:

When I display the extended ASCII character set with a QuickC font,
the characters do not match my chart for the characters. However, when
I watch an array of the extended characters in the watch window, they
are the same as my chart.

Response:

There are three parts to this response:

1. What happens in the watch window, versions 2.00 and 2.01

2. The fonts and Presentation Graphics (PG) default font in QuickC
   version 2.00

3. The fonts and PG default font in QuickC Version 2.01

What Happens in the Quick Environment
Watch Window, Versions 2.00 and 2.01
-------------------------------------

The Quick environment's watch window uses the system character set,
not fonts. The default system character set in the United States is
codepage 437, a table of 256 character correspondence codes. Codepage
437 matches the IBM extended character set so the watch window
displays the standard characters.

It is possible to override the default system character set with DOS's
command to change codepage (CHCP). However, a call to _setvideomode()
-- required when you use fonts -- will reset the system character set
to the default.

The Fonts and PG Chart Default Font in QuickC Version 2.00
----------------------------------------------------------

The .FON files contain the ANSI character set, not the extended ASCII
character set. They match the ASCII character set only from hex 20
through hex 7E. When you use _outgtext() to display any of the
extended characters, only characters from hex 20 through hex 7E will
match your ASCII chart; for example, the function _outgtext() displays
the ANSI characters. The function _outtext() displays the ASCII
characters.

The PG Chart default font uses a bitmap that is the same as codepage
437. Extended characters you display with the default font will match
the extended ASCII chart.

The Fonts and PG Chart Default Font in QuickC Version 2.01
----------------------------------------------------------

The .FON files are the same as Version 2.00 .FON files. However, in
QuickC Version 2.01, the _outgtext() function maps the ANSI character
set onto codepage 850. Codepage 850 is a multilingual character set
(as distinct from codepage 437, which is the U.S. character set).

While not an exact match of the extended ASCII character set, codepage
850 matches more ASCII chart characters than the ANSI character set
does. Specifically, codepage 850 and the ASCII chart share the
accented vowels used in European languages. When you use _outgtext()
to display extended characters using fonts in Version 2.01, more of
the characters will match the ASCII chart than when you use Version
2.00. (The function _outtext() displays the ASCII characters in
Version 2.01 as it does in Version 2.00.)

In Version 2.01 the PG Chart default font maps to codepage 850
(instead of codepage 437).

The QuickC .FON files are identical to the .FON files used in the
Microsoft Windows operating environment. You can use any fonts files
that are compatible with Windows with QuickC. You can find more
information on fonts in "C for Yourself," Chapter 14, "Fonts."

For more information on the ANSI characters, refer to Page 152 in
"Programming Windows," Chapter 4, "The Keyboard."

You can find additional information on codepages in "The MS-DOS
Encyclopedia."

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