FIX: Transform on String Greater Than 255 Crashes VFP 6.0

ID: Q190792

The information in this article applies to:

Microsoft Visual FoxPro for Windows, version 6.0

SYMPTOMS

Microsoft Visual FoxPro causes an exception error when using the Transform() function to transform a string greater than 255 characters.

RESOLUTION

The following workaround should work for strings of arbitrary length and has being tested with "@!" picture.

Sample Code


   CLEAR
   m.string = REPLICATE("HelloWorld", 26)
   ? "Initial string length: ", LEN(m.string)
   m.string = transgt255(m.string, "@!")
   ? "Return value from function: ", m.string
   ? "Length of returned string: ", LEN(m.string)

   * Function TRANSGT255
   * Purpose: Apply a string transformation to a string longer than 255
   * characters passed: string to transform (lcText), transform string to
   * apply (lcTransType).
   * Returns: Transformed string (lcRetString).

   FUNCTION transgt255

   PARAMETERS lcText, lcTransType

   * Define a string length safely smaller than 255, doesn't matter for
   * these purposes.

   #DEFINE MAX_LENGTH 253

   liNumPasses = INT(LEN(lcText) / MAX_LENGTH)
   liLastPass = MOD(LEN(lcText), MAX_LENGTH)

   lcRetString = ""
   FOR i = 1 TO liNumPasses
      lcWorkString = SUBSTR(lcText, (i - 1) * MAX_LENGTH + 1, MAX_LENGTH)
      lcRetString = lcRetString + ;
         TRANSFORM(lcWorkString, (lcTransType))
   NEXT

   lcWorkString = RIGHT(lcText, liLastPass)
   lcRetString = lcRetString + ;
      TRANSFORM(lcWorkString, (lcTransType))

   RETURN lcRetString

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

MORE INFORMATION

Steps to Reproduce Behavior

Create a .prg file.

Place the following code in the .prg file:


lcText=REPLICATE("HelloWorld",26)
? LEN(lcText)
? TRANSFORM(lcText,"@!")

Save and run the .prg file.

NOTE: Visual FoxPro 6.0 experiences an exception error and terminates. When changing the value of 26 to 25 in the Replicate() function, the preceding code runs correctly without any error.

The error message displayed is partially dependent on the file that the code is contained within. Assuming that the preceding code is in a program named Test.prg and the program is located in the C:\FoxData directory, the error message would be as follows:

Fatal error: Exception code = C0000005
Called from - test line 3 {C:\FoxData\test.prg}

Additional query words:

Keywords : kbVFp600 kbVFp600bug kbXBase kbGrpFox kbDSupport
Version : WINDOWS:6.0
Platform : WINDOWS
Issue type : kbbug