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Q38494: Beep or Hang Using RETURN without GOSUB with No BC /D Debug

Article: Q38494
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 | mspl13_basic
Last Modified: 30-NOV-1988

Using a RETURN statement within a subprogram without an accompanying
GOSUB statement is a programming error.

A program with this syntax error will actually compile (in BC.EXE) and
link without error. However, the resulting executable program will
hang in various ways, ranging from a continuous beep from the speaker
to the printing of random ASCII characters on the screen. The bad
symptoms will only occur if you compile without the /D (debug) option.
The error is successfully trapped at run time if you compile with the
/D (debug) option.

The syntax error also is caught in the QB.EXE environment at run time,
because the editor is always in debug mode.

Microsoft has confirmed this to be a problem in QuickBASIC Versions
4.00, 4.00b, and 4.50, and to Microsoft BASIC Compiler Versions 6.00
and 6.00b for MS-DOS and MS OS/2. We are researching this problem and
will post new information as it becomes available.

The problem symptoms occur whether the program is compiled with or
without the BC /O (stand-alone) option. You will need to run in QB.EXE
or compile with the /D (debug) option to uncover programming errors
such as these.

The following is a code example:

DECLARE SUB foo ()
PRINT "In Main Program"
CALL foo
PRINT "After SUB"
END

SUB foo
  PRINT "In Sub"
  RETURN  ' Program will hang on this statement.
          ' This RETURN should be deleted; it is a programming error.
END SUB

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