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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