Q47643: Improper IF Statement Syntax Can Hang QB.EXE 4.00 Environment

Article: Q47643
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 SR# S890614- | mspl13_basic
Last Modified: 28-FEB-1990

An illegally formed IF statement may hang the QuickBASIC environment
during the binding stage. When you move the cursor to the IF
statement, the reserved words will not be converted to uppercase
letters, and there will be no syntactic error message generated.

The computer hangs only when the program is executed inside the
QuickBASIC environment. The compiler correctly generates several error
messages for the illegally formed IF statement.

Microsoft has confirmed this to be a problem in the QB.EXE editor in
QuickBASIC Versions 4.00, 4.00b, and 4.50, and in the QB.EXE editor
that comes with Microsoft BASIC Compiler Versions 6.00 and 6.00b
(buglist6.00, buglist6.00b). This problem was corrected in the QBX.EXE
environment of Microsoft BASIC Professional Development System (PDS)
Version 7.00 for MS-DOS and MS OS/2 (fixlist7.00). QBX.EXE correctly
identifies that the syntax is in error.

Code Example
------------

The following code sample reproduces the problem:

   REM *** SAMPLE PROGRAM

   if a$ = "1" goto d$ = "larry"

When you type this program in the QB.EXE editor and press the ENTER
key, reserved words stay as entered and fail to automatically shift to
uppercase letters. Running the program hangs the computer.

If you attempt to enter the above code in the QBX.EXE environment of
BASIC PDS 7.00, the environment correctly highlights the second string
variable and reports "Expected: Label or Line-number".

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