Q30858: QuickBASIC 4.x Procedure Name Followed By Colon Not Executed

Article: Q30858
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist4.00 buglist4.00b buglist4.50 b_basiccom | mspl13_basic
Last Modified: 20-SEP-1990

When you use the implied CALL syntax, a SUBprogram procedure name
followed immediately by a colon is mistaken for a label name. This
prevents the SUBprogram from being executed. The problem occurs both
inside the QB.EXE environment and when compiled from BC.EXE.

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 (buglist6.00, buglist6.00b) for MS-DOS and MS OS/2; 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.

This is not an issue in QuickBASIC version 3.00 and earlier versions,
because these versions require the CALL statement to execute
SUBprogram procedures. The implied CALL syntax was added to QuickBASIC
version 4.00. An "implied CALL" is where a procedure name is invoked
without a preceding "CALL" statement, then followed by parameters
passed in a list without surrounding parentheses.

The following are two workarounds for this problem:

1. Place the command following the procedure name on a new line so
   that the colon is not necessary.

2. Use an explicit CALL statement to invoke the procedure.

The following code example demonstrates the problem:

   DECLARE SUB subtest ()
   CLS
   PRINT "this is the main"
   subtest: PRINT "the end"

   SUB subtest
   PRINT "this is sub test"
   END SUB

The procedure (SUBTEST) above will not be executed because the
compiler mistakes the procedure name followed by a colon for a label
name.

The following code will execute correctly:

   DECLARE SUB subtest ()
   CLS
   PRINT "this is the main"
   call subtest: PRINT "the end"

   SUB subtest
   PRINT "this is sub test"
   END SUB

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.