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Posted 19 Feb 2006

Numeric TextBox

, 1 Apr 2006
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The article disucusses a new way to let a TextBox only accept numeric values, without using custom controls.

Sample Image - NumericTextBox.gif


Many of us have faced a situation where we want the user to enter a number (an integer or a double) in a TextBox, thus seeking a way to prevent him from inserting invalid characters. Almost all of the available solutions required to use a custom control inherited from TextBox control. Regarding the fact that the developers sometimes (or perhaps often!) decide to add this facility to their TextBoxes after they have added several TextBox controls, and added many other lines of code to their project based on these controls names, these solutions are practically of limited use. (The programmer needs to remove all TextBoxes, add the new custom control instead of each of them, and make all the required changes to the code.)

Considering that, I broke the project to two blocks:

  1. To validate each character a user presses on the keyboard, check if its addition to the current value of the TextBox will still result in a numeric value, and prevent the character to be added to the TextBox value if the answer is no.
  2. To perform the validation on pasting into the TextBox. Pasting could be done through pressing CTRL+V, SHIFT+INSERT or using the right-click context menu.

The first issue can be handled using the onKeyPress event of the TextBox. For the second part, unfortunately, we don't have an onPaste event. I used a brilliant method dedicated in this Experts-Exchange thread.

Using the code

You will need to set the numericTextboxKeyPress sub to handle the onKeyPress event for all TextBoxes you want to validate. This will handle the input characters as the user types them.

The creative TextBoxOnChange class handles the paste event for the TextBoxes. For each TextBox on which you want to handle the paste event, you should add a line of code like this:

//Example of adding an onPaste handler
Dim onPaste1 As New TextBoxOnPaste(Me.TextBox1)

I added two checkboxes to the demo project source code to facilitate your learning how to use the code for multiple checkboxes.


25 Feb 2006 : Minor bug fixes.

19 Feb 2006 : Original article submitted.


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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About the Author

Hojjat Salmasian
Web Developer
United States United States
No Biography provided

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Questionvs2005 only? Pin
GaryMinor222-Feb-06 11:31
memberGaryMinor222-Feb-06 11:31 
AnswerRe: vs2005 only? Pin
Christian Graus22-Feb-06 11:54
protectorChristian Graus22-Feb-06 11:54 
AnswerRe: vs2005 only? Pin
Hojjat Salmasian22-Feb-06 17:08
memberHojjat Salmasian22-Feb-06 17:08 
Questionwhat about coma ? Pin
scalpa9822-Feb-06 1:28
memberscalpa9822-Feb-06 1:28 
AnswerRe: what about coma ? Pin
Hojjat Salmasian22-Feb-06 6:40
memberHojjat Salmasian22-Feb-06 6:40 
GeneralRe: what about coma ? Pin
scalpa9822-Feb-06 7:48
memberscalpa9822-Feb-06 7:48 
GeneralRe: what about coma ? Pin
Hojjat Salmasian22-Feb-06 17:04
memberHojjat Salmasian22-Feb-06 17:04 
GeneralRe: what about coma ? Pin
scalpa9822-Feb-06 20:18
memberscalpa9822-Feb-06 20:18 
GeneralRe: what about coma ? Pin
Hojjat Salmasian23-Feb-06 5:33
memberHojjat Salmasian23-Feb-06 5:33 
AnswerRe: what about coma ? Pin
Rob_III4-Sep-06 6:19
memberRob_III4-Sep-06 6:19 

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