Q27277: IF Statement Missing Colon Not Always Trapped at Compile Time

Article: Q27277
Product(s): See article
Version(s): 3.00 4.00 4.00b
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom buglist3.00 buglist4.00 buglist4.00b fixlist4.50 | mspl13_basic
Last Modified: 17-JAN-1990

The program below, which is missing a colon (:) before the GOTO
statement in the IF statement, correctly gives the run-time error
"Expected: end-of-statement" in the QuickBASIC Version 4.00 editor.

However, when compiled from the DOS command line with BC.EXE and
LINKed into an EXE program, the EXE program runs successfully without
an error, printing "a=1" as if the missing colon were present.

The same behavior occurs when compiling with QB.EXE Version 3.00 using
the separate compilation method. (There is no BC.EXE in 3.00).

To work around the problem, detect the missing colon by running and
debugging the program in the editor before compiling to an EXE file.

Microsoft has confirmed this to be a problem in QuickBASIC Versions
3.00, 4.00, and 4.00b, and in Microsoft BASIC Compiler Versions 6.00
and 6.00b (buglist6.00, buglist6.00b) for MS-DOS and OS/2. This
problem was corrected in QuickBASIC Version 4.50 and in Microsoft
BASIC Professional Development System Version 7.00 for MS-DOS
(fixlist7.00).

The following is the sample program:

if a = 0 then a = 1 goto ending   ' A colon is missing before the GOTO.
print "should not be seen"
ending:
print "a =";a
system

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