Visual Basic Code of the Week (COTW)
http://www.codeoftheweek.com
Issue #33
All content and source code is Copyright (c) 1998 by C&D Programming Corp. No part of this issue can be reprinted or distributed in any manner without express written permission of C&D Programming Corp.

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It will be available in May 1998. For a limited time we will be taking pre-orders for only $29.95 for run-time DLL's and $129.95 for complete source code (of course you won't be charged until it ships). After this initial offering the price will increase to $49.95 and $199.95 respectively. The first version of this product will require Visual Basic 5. If you are interested, please email noise@codeoftheweek.com and we will provide complete details on placing your order or use our order form at http://www.codeoftheweek.com/order.html . Just select NoiseMaker Special Offer from the Subscription Type field.


Requirements for this Issue

The source code in this issue is designed for all versions of Visual Basic.

In this Issue

We discuss some ways to do keystroke validations. It is geared more towards the beginning VB programmer.

Keystroke Validation Module

Description

This module contains several short routines that are commonly used in the KeyPress event of various controls, such as the TextBox control. If you want this code to work in VB 3 or earlier you will need to change the return data type from Boolean to Integer.

Declaration

Function IsAlphaKey(KeyAscii As Integer) As Boolean
Function IsNumericKey(KeyAscii As Integer) As Boolean
Function IsEditingKey(KeyAscii As Integer) As Boolean
Function IsAlphaNumericKey(KeyAscii As Integer) As Boolean

What they do...

IsAlphaKey checks to make sure KeyAscii is a letter from A to Z. This particular routine will not work for alphabets other than US English. If anyone can modify them appropriately for other languages please email us and we will post them for all our subscribers.

IsNumericKey checks to make sure KeyAscii is a number from 0 to 9. It also checks for a negative sign, decimal character and comma.

IsEditingKey checks to make sure KeyAscii is a backspace character.

IsAlphaNumericKey called IsAlphaKey and IsNumericKey together and therefore validates the character as described in IsAlphaKey and IsNumericKey.

Parameters

Returns

True or False depending on whether keystroke is valid or not.

Sample Usage

You would put something like this in the KeyPress event of a control to make sure the user can only enter letters or a backspace.

    If IsAlphaKey(KeyAscii) or IsEditingKey(KeyAscii) then
        Exit Sub
    Else
        KeyAscii = 0 ' throw away keystroke
    End If

Source Code

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Summary

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