Q28037: RESUME NEXT with Single-Line DEF FN RESUMEs Wrongly in QB.EXE

Article: Q28037
Product(s): See article
Version(s): 4.00 4.00b
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom buglist4.00 buglist4.00b fixlist4.50 | mspl13_basic
Last Modified: 31-JAN-1990

In the QB.EXE editor, when an error occurs inside a single-line DEF
FN function, RESUME NEXT returns control to an unexpected location.

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

In QB.EXE, the code traps the error but resumes to the FOR before it
exits the loop. (When compiled with BC.EXE, the EXE program handles
the problem correctly.)

As a workaround, use a multi-line function or FUNCTION procedure
instead of a single-line DEF FN function.

The problem only occurs with single-line DEF FN and RESUME NEXT. The
interpreter treats line 20 as the current line (ERL) and resumes at
line 30. The BASIC compiler says 40 is the current line (ERL) and
resumes at 50.

The following is a code sample:

   10 on error goto 900
   20 def FnTest(A) = 1-SQR(A)
   30 FOR I=4 to -2 STEP -1
   40    PRINT I, FNTEST(I)
   50 NEXT
   60 END

   900 PRINT "No negatives"
   910 RESUME NEXT

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