Article ID: 50220
Article Last Modified on 8/16/2005
APPLIES TO
- Microsoft QuickBasic 4.5 for MS-DOS
- Microsoft BASIC Professional Development System 7.0
This article was previously published under Q50220
SYMPTOMS
There is a problem in the QuickBasic Version 4.50 environment with passing a FUNCTION procedure as a parameter to a user-defined function that calls a SUBprogram when the FUNCTION and SUBprogram procedures are located in a Quick library. A "String space corrupt" error displays, and the program returns to DOS. This problem occurs only when running the program a second time [using any combination of the ALT+R+R (Restart), F8, F5 (ALT+R+N), or SHIFT+F5 (ALT+R+S) (Start) keys]. The problem doesn't occur in compiled .EXE programs.
STATUS
Microsoft has confirmed this to be a bug in the QuickBasic environment (QB.EXE) in Version 4.50. This problem was corrected in the QBX.EXE environment of Microsoft Basic Professional Development System (PDS) Version 7.00 for MS-DOS and MS OS/2 (fixlist7.00).
MORE INFORMATION
You can work around this problem by assigning the value returned by the BN$ FUNCTION to a temporary value and passing this temporary value when you invoke the FNOPEN% user-defined function (as demonstrated in MAIN.BAS below).
The "String space corrupt" error is not generated in any of the following cases:
- If QLIB.BAS (shown below) is loaded as a secondary module instead of as a .QLB (Quick library)
- When the two modules (shown below) are compiled into an .EXE (using QLIB.LIB or QLIB.OBJ) and run as an .EXE
- When QuickBasic Version 4.00 or 4.00b is used
The following programs, MAIN.BAS and QLIB.BAS, demonstrate the problem. MAIN.BAS is the module loaded into the environment, and QLIB.BAS is the Quick library, which is loaded in with the /L invocation switch (for example, QB MAIN /L QLIB).
MAIN.BAS
DECLARE FUNCTION BN$ (X$)
DECLARE SUB SOPEN (KAN%, K$, BEST$, RECL%)
DEF FNOPEN% (KAN%, K$, BEST$, RECL%)
CALL SOPEN(KAN%, K$, BEST$, RECL%)
END DEF
CLS : LOCATE 21, 1
'Statement that causes the "String space corrupt" error:
FS% = FNOPEN%(2, "S", BN$("XXXXACTR"), 256)
'Workaround to eliminate the "String space corrupt" error:
'TEMP$ = BN$("XXXXACTR")
'FS% = FNOPEN%(2, "S", TEMP$, 256)
QLIB.BAS
DECLARE FUNCTION BN$ (X$)
DECLARE SUB SOPEN (KAN%, K$, BEST$, RECL%)
FUNCTION BN$ (X$)
BN$ = "C:0001" + MID$(X$, 5)
END FUNCTION
SUB SOPEN (KAN%, K$, BEST$, RECL%)
PRINT BEST$
END SUB
Additional query words: QuickBas BasicCom SR# S891006-116 buglist4.50 B_BasicCom
Keywords: KB50220
