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Q138499: How to Limit the Number of Characters Typed in a Combo Box

Article: Q138499
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s): 
Keyword(s): 
Last Modified: 11-FEB-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
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SUMMARY
=======

You can limit the number of characters that a user can type into a text box by
using the InputMask property. However, this property does not exist for a combo
box. This article shows shows by example how to limit the number of characters
typed in a combo box by placing code in the KeyPress event.

MORE INFORMATION
================

Step-by-Step Example
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1. Create a new form.

2. On the Form menu, click New Property, and name the new property numb.

3. Place a combo box on the form, and set its ControlSource, RowSourceType, and
  RowSource properties.

4. Place at least one other control on the form.

5. Place the following code in the KeyPress event for the combo box to limit the
  number of characters entered into the combo box to 3:

    IF nKeyCode=13 OR nKeyCode=9   && test for ENTER or TAB
       THISFORM.numb=0              && and reset numb
     ELSE
       IF !(nkeyCode=127 OR ;       &&  BACKSPACE
         nkeyCode=7 OR ;            &&  DELETE
         nkeyCode=6 OR ;            &&  END key
         nkeyCode=19 OR ;           &&  LEFT ARROW
         nkeyCode=4 OR ;            &&  RIGHT ARROW
         nkeyCode=1)                &&  HOME key
         THISFORM.numb=THISFORM.numb+1  && if not one of the above increment

           IF THISFORM.numb=4       && When 4 characters have been entered
             THISFORM.numb=0        && reset numb to zero and flash a message
             ?? CHR(7)              && ring the bell
             =MESSAGEBOX("Enter only 3 characters")
             NODEFAULT              &&  do not enter the character typed.
           ENDIF
       ENDIF
     ENDIF

Additional query words: VFoxWin mask format

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Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbVFP300
Version           : WINDOWS:3.0

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