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Q190792: FIX: Transform on String Greater Than 255 Crashes VFP 6.0

Article: Q190792
Product(s): Microsoft FoxPro
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): kbvfp600 kbvfp600bug kbXBase kbGrpDSFox kbDSupport
Last Modified: 19-JAN-2000

-------------------------------------------------------------------------------
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
---------------------------

1. Create a .prg file.

2. Place the following code in the .prg file:

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

3. 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 kbGrpDSFox kbDSupport 
Technology        : kbVFPsearch kbAudDeveloper kbVFP600
Version           : WINDOWS:6.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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