PRB: INDEX ON with Variable Length Tag May Behave Differently

ID: Q165068

The information in this article applies to:

Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a

SYMPTOMS

When attempting to create a variable length index tag in Visual FoxPro version 5.0, one of the following error messages may occur:

Cannot access characters beyond string

-or-

Invalid key length

This behavior does not occur in earlier versions of FoxPro.

According to the Visual FoxPro online Help, variable length index keys are not supported in Visual FoxPro. As stated in the Help file:

If you attempt to build an index with a key that varies in length, the key will be padded with spaces. Variable-length index keys aren't supported in Visual FoxPro.

In the case of Visual FoxPro 5.0, it appears that any variable length key is not being padded.

RESOLUTION

The following code creates an index tag from a variable length key but is padded to a specific length:


   SET TALK OFF  && If TALK isn't turned off, an error will occur.
     SET SAFETY OFF
      CREATE TABLE oneproduct ;
           (PRODUCT c(15))
      SET SAFETY ON
      INSERT INTO oneproduct (PRODUCT) VALUES ("01PAN AG-1310")

       INDEX ON PADR(SUBSTR(product, AT(" ", product)+1), ;
          LEN(product)+2 ," ") TAG prod

STATUS

Microsoft is researching this behavior and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Steps to Reproduce Behavior

The following code illustrates the problem with creating a variable length index tag:


   SET SAFETY OFF
   CREATE TABLE oneproduct ;
        (PRODUCT c(15))
   SET SAFETY ON
   INSERT INTO oneproduct (PRODUCT) VALUES ("01PAN AG-1310")

   * The following code works without error in versions prior to 5.0
   INDEX ON SUBSTR(PRODUCT,AT(" ",PRODUCT)+1) TAG prod1
   INDEX ON RIGHT(PRODUCT,LEN(PRODUCT)-AT(" ",PRODUCT)) TAG prod2

   * The following code works without error:
   *!*   SET TALK OFF
   *!*   INDEX ON PADR(SUBSTR(product, AT(" ", product)+1), ;
   *!*     LEN(product)+2 ," ") TAG prod

The first INDEX ON line causes the error message,

Cannot access characters beyond string.

The second INDEX ON line causes the error message,

Invalid key length.

This behavior does not occur in earlier versions of FoxPro and the indexes are created without error.

Additional query words: previous kbvfp500

Keywords : kbVFp FxprgTable
Version : WINDOWS:5.0,5.0a
Platform : WINDOWS
Issue type : kbprb