Q28044: BC.EXE Cannot Compile ASCII 1 or 2 in Fast Load Format Files

Article: Q28044
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom buglist4.00 buglist4.00b buglist4.50 | mspl13_basic
Last Modified: 20-SEP-1990

Files saved in the QuickBASIC Fast Load format that contain an ASCII 1
or 2 byte value (control code) typed into a comment or quoted string
constant (such as using CTRL+P+A for ASCII 1 or CTRL+P+B for ASCII 2
in QB.EXE or QBX.EXE) cannot be compiled with BC.EXE. BC.EXE gives a
"Statement Unrecognizable" error at compile time. (The ASCII 1 or 2
control characters compile correctly with BC.EXE when saved in Text
format. Other control character bytes compile successfully with BC.EXE
when saved with Fast Load or Text format.)

Microsoft has confirmed this to be a problem in QuickBASIC versions
4.00, 4.00b, and 4.50 for MS-DOS; in Microsoft BASIC Compiler versions
6.00 and 6.00b for MS-DOS and MS OS/2 (buglist6.00, buglist6.00b); and
in Microsoft BASIC Professional Development System (PDS) versions 7.00
and 7.10 for MS-DOS and MS OS/2 (buglist7.00, buglist7.10). We are
researching this problem and will post new information here as it
becomes available.

In BC.EXE version 4.50 and in Microsoft BASIC PDS versions 7.00 and
7.10 for MS-DOS and MS OS/2, you do not get a compile-time error (for
the Fast Load format file), but the BC.EXE compiler strips the ASCII 1
or 2 byte out of quoted strings, and the byte is not printed on the
screen at run time. To work around this problem, you can use the CHR$
function, as follows:

   CHR$(1)
or
   CHR$(2)

Press CTRL+P followed by a control character to type control
characters into the QB.EXE or QBX.EXE editor.

Related Note: The following limitation is by design, and distinct from
the above software problem. ASCII byte values 1 (CTRL+P+A), 2
(CTRL+P+B), and 3 (CTRL+P+C) can be placed in DATA statements, but
your variable in the READ statement must be a string variable (such as
X$) to receive the control character byte. Incorrectly using a numeric
variable in the READ statement to receive these characters will give
"Out of Data" in QB.EXE in QuickBASIC 4.00 and 4.00b, and "Syntax
Error" in QB.EXE in QuickBASIC 4.50. Also in 4.00 and 4.00b, you get
"Out of Data" unless you put double quotation marks around the byte
values; in 4.50, the double quotation marks are optional around the
byte values in the DATA statement.

In contrast, when you use direct numeric constants such as 1, 2, and 3
(DATA 1,2,3), you need to READ into a numeric variable.

Example 1
---------

Compiling the following statement in BC.EXE demonstrates the problem.
Type CTRL+P followed by CTRL+A (that is, CTRL+P+A) to put an ASCII 1
into the quoted string in the QB.EXE editor. CTRL+P+B puts an ASCII 2
into a quoted string in QB.EXE. The ASCII 1 appears as a happy face
symbol, and ASCII 2 appears as an inverse-video happy face.

   PRINT "< CTRL+P+A > < CTRL+P+B >"

Depending upon your usage of the ASCII 1 or 2 byte, you can use any of
the following to work around the problem:

1. Use the CHR$ function as a workaround to embed ASCII 1 or 2 into a
   string variable. For example, the following program prints happy
   faces in both the QB.EXE editor and in an .EXE program in
   QuickBASIC versions 4.00, 4.00b, 4.50, BASIC compiler 6.00 and
   6.00b, and BASIC PDS version 7.00:

      HAPPY$=CHR$(1)+CHR$(2)
      PRINT HAPPY$ + " TEST " + HAPPY$

2. The ASCII 1 or 2 bytes can be successfully embedded in quoted
   strings or remarks if you run in the QB.EXE version 4.00, 4.00b, or
   4.50 editor, or the QBX.EXE editor supplied with BASIC PDS version
   7.00.

3. If the file is saved as Text instead of in Fast Load format, it
   compiles without error in BC.EXE in QuickBASIC 4.00, 4.00b, or
   4.50. This corrects the problem if you are just using ASCII 1 or 2
   in remarks (REM or ' statements) in the source code. However, the
   ASCII 1 or 2 character will be stripped from any quoted strings in
   your program if you run from an .EXE program.

4. In QuickBASIC version 4.50 and BASIC PDS version 7.00, BC.EXE
   compiles the program correctly regardless of Fast Load format. This
   corrects the problem if you are just using ASCII 1 or 2 in remarks
   (REM or ' statements) in the source code. However, the ASCII 1 or 2
   character will still be stripped from any quoted strings in your
   program if you run from an .EXE program.

Example 2
---------

The following program is another demonstration of the problem. Type
this program in the QB.EXE or QBX.EXE editor, and choose the Make EXE
File command on the Run menu.

   ' In QB.EXE and QBX.EXE, CTRL+P can be used to embed control
   '   characters:
   A$ = "Press: CTRL+P+A" + "Press: CTRL+P+B"
   PRINT A$
   OPEN "JUNK.TST" FOR OUTPUT AS #1
   PRINT#1,A$
   CLOSE

Running the .EXE version of this program shows that the ASCII 1 and 2
happy face characters do not display on the screen or write to the
file because they were stripped out at compile time. After running
this program, perform the following command in DOS to display the
characters written to the file:

   TYPE JUNK.TST

A simple workaround is to replace the first line of the program with
the following:

   A$ = CHR$(1) + CHR$(2)

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