BUG: Creating 500 Instances of a Form Class Causes IC Error

ID: Q135519

The information in this article applies to:

Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0

SYMPTOMS

Attempts to create 500 instances of a form class containing a small number of controls in a FOR loop causes an "Internal Consistency Error" (ICE).

The number of instances it can instantiate from a form class before an ICE occurs depends on the amount of RAM and the operating system on your computer.

NOTE: On 16-bit operating systems, such as Windows for Workgroups 3.11, you may get the following error message instead of an ICE:

   There is not enough memory to complete this operation.

In Visual FoxPro 5.0, the message "Too Many Windows Open" appears and the program ends. FoxPro does not exit.

In Visual FoxPro 5.0a, the message "Too Many Windows Open" appears, and the program removes all the instances of the form class from the screen. FoxPro does not abnormally terminate.

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Steps to Reproduce Problem

1. Enter the following command in the Command window:

   CREATE CLASS x OF x AS FORM

2. Add the following objects to the form:

   Text Box
   list box
   Option Group
   check box
   Spinner

3. Press CTRL+W to save the class, and exit from the Class Designer.

4. Enter the following command in the Command window:

   MODIFY COMMAND mul_inst.prg

5. Type the following code into Mul_Inst.prg:

   SET CLASSLIB TO X
   PRIVATE i
   FOR i = 1 TO 500
      string = "x" + ALLTRIM(STR(i))
      &string = CREATEOBJECT('x')
      IF &string..Left = 500
          &string..Left = 1
      ENDIF
      &string..Left = &string..Left+3
      &string..Caption = string
      &string..Show
   NEXT i

6. Enter the following command in the Command window:

   DO MUL_INST.PRG

Additional query words: kbvfp300b kbvfp500 kbvfp600

Keywords          : kbVFp kbVFp300bbug kbVFp500abug kbVFp500bug buglist3.00 FxprgGeneral kbbuglist
Version           : WINDOWS: 3.0,3.0b,5.0,5.0a,6.0
Platform          : WINDOWS
Issue type        : kbbug