Q31297: A GOTO Inside SELECT CASE Incorrectly Executes ELSE Block

Article: Q31297
Product(s): See article
Version(s): 4.00 4.00b
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist4.00 buglist4.00b fixlist4.50 B_BasicCom | mspl13_basic
Last Modified: 5-DEC-1989

In a compiled .EXE program, if a GOTO statement is executed inside of
a SELECT CASE block, when that CASE is executed as expected, the CASE
ELSE is also (wrongly) executed.

However, the program behaves correctly when run in the QB.EXE editor.

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

The following code example demonstrates this problem:

     x=1
     select case x
      case 1
       print "one"
       goto 100
100:   print "hundred"
      case 2
       print "two"
      case else
       print "else"
     end select

The (incorrect) output from the above program as an .EXE is as
follows:

   one
   hundred
   else

The (correct) output when run in the QuickBASIC environment is as
follows:

   one
   hundred

You can work around the problem of using GOTO and a label in a CASE by
ending that CASE with a GOTO to a label that is after the END SELECT
statement, as follows:

     x=1
     select case x
      case 1
       goto 100
       print "never prints"
100:   print "hundred"
       goto 200   ' This GOTO is the workaround solution.
      case 2
       print "two"
      case else
       print "else"
     end select
200: print "After END SELECT"

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