Q43092: Underscore (_) Not OK in Variable Name or Line Continuation

Article: Q43092
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S890327-20 B_BasicCom | mspl13_basic
Last Modified: 15-DEC-1989

The underscore character (_) is not allowed within a QuickBASIC
variable, SUBprogram, or FUNCTION name in all versions of QuickBASIC.
Also, you cannot type an underscore as a line continuation character
within the QB.EXE environment of QuickBASIC Versions 4.00, 4.00b, and
4.50, the QB.EXE environment in Microsoft BASIC Compiler Versions 6.00
and 6.00b, or the QBX.EXE environment in Microsoft BASIC PDS Version
7.00.

If an editor other than QB.EXE / QBX.EXE is used to write your
program, the underscore character is recognized as a valid line
continuation character by the BC.EXE compiler (but still cannot be
used within variable, SUBprogram, or FUNCTION names).

QB.EXE / QBX.EXE can load text files that use underscores for line
continuation, but the underscore is stripped out and the continued
lines are concatenated. Total concatenated line length is limited to
255 characters in QB.EXE / QBX.EXE and BC.EXE.

This information applies to QuickBASIC 4.00, 4.00b, and 4.50, the
QB.EXE environment included with the BASIC compiler 6.00 and 6.00b,
and the QBX.EXE environment of BASIC PDS 7.00.

QuickBASIC Versions 3.00 and earlier allowed you to continue lines
with an underscore (_) character. However, in Versions 4.00 and later,
the underscore character is not allowed, due to conflicts with the
threaded p-code used within the environment and with the ability to
perform interlanguage calling, especially with Microsoft C.

If you create your program within another editor using the underscore
as a line continuation character, and then attempt to load the program
into the QuickBASIC environment Version 4.00 or later (or the QBX.EXE
environment of BASIC PDS 7.00), the underscores used as line
continuation characters are removed and the fragments of lines
separated by the underscore are concatenated into one line.

For example, write the following program using an editor other than
QB.EXE 4.00 or later (or QBX.EXE):

    A = _
    5 * _
    B
    END

If the above program is loaded into the Version 4.00 or later QB.EXE
environment or the QBX.EXE of BASIC PDS 7.00, it will be converted to
the following:

    A = 5 * B
    END

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