Q28154: A RETURN Without a GOSUB in a Subprogram Hangs in EXE

Article: Q28154
Product(s): See article
Version(s): 6.00    | 6.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | | mspl13_basic
Last Modified: 11-JUL-1990

Executing a RETURN statement without a corresponding GOSUB in a
subprogram hangs an EXE program when compiled without the BC /D
option. You must compile with the BC /D option (or compile in the
QuickBASIC environment) to trap a "RETURN without GOSUB" programming
error (just as you must use BC /D to trap array bounds violations).

This information applies to BC.EXE in Microsoft BASIC Compiler
versions 6.00 and 6.00b for MS-DOS and MS OS/2, to BC.EXE in Microsoft
BASIC Professional Development System (PDS) version 7.00 for MS-DOS
and MS OS/2, and to BC.EXE in QuickBASIC versions 4.00, 4.00b, and
4.50 for MS-DOS.

Compile the test program below with BC.EXE and then link it. If you
compile with the BC /D option, the program gives run-time error,
"RETURN without GOSUB." If you don't compile with /D, the program
hangs the computer at run time without telling you about your
programming mistake.

To avoid hanging due to a programming error like this, use the QB.EXE
or QBX.EXE environment as a debugger, since the interpreter
environment correctly traps the "Return without GOSUB" error. The
program should be modified to remove the "Return without GOSUB"
programming error.

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

' test.bas
   defint a-z
   declare sub atest ( x )

     i = 1
     print i
     call atest (i)
     print i
   end

   sub atest ( j )
      print j
      j = 2
      print j
      return
   end sub

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