Underscore (_) Not OK in Variable Name or Line Continuation (43092)

SUMMARY

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.

MORE INFORMATION

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