STATIC FUNCTION Fails to Retain Value Between Invocations (46180)

SYMPTOMS

A function that has been declared with the STATIC attribute should retain its value between calls. When a STATIC function is called and assigned a value, subsequent calls to the function that do not assign a new value to the function should always return the previous value, even if you leave the function with an EXIT FUNCTION statement. This behavior is correctly exhibited by programs compiled with BC.EXE.

However, when you attempt the same procedure in the QB.EXE or QBX.EXE environment, a STATIC FUNCTION fails to retain its value in multiple invocations, and incorrectly returns a 0 (zero) or null string, depending on the type of the function.

STATUS

Microsoft has confirmed this to be a bug in the QB.EXE environment of Microsoft QuickBasic versions 4.00, 4.00b, and 4.50; in the QB.EXE environment of Microsoft Basic Compiler versions 6.00 and 6.00b (buglist6.00, buglist6.00b); and in the QBX.EXE environment of Microsoft Basic Professional Development System (PDS) versions 7.00 and 7.10 (buglist7.00, buglist7.10). We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

The following sample program demonstrates the problem:

   x% = staticfun%(1)
   PRINT x%   ' Should print 5.
   x% = staticfun%(0)
   PRINT x%   ' Should print 5.
   END

   FUNCTION staticfun%(parm%) STATIC
     IF parm% = 0 THEN
       EXIT FUNCTION
     ELSE
       staticfun% = 5
     END IF
   END FUNCTION

When this program is compiled with BC.EXE, it correctly prints the values 5 and 5. From inside the QuickBasic QB.EXE or QBX.EXE environment, it incorrectly prints 5 and 0.