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Numeric TextBox

, 1 Apr 2006 141.2K 4.3K 49
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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

Introduction

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.

History

25 Feb 2006 : Minor bug fixes.

19 Feb 2006 : Original article submitted.

License

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.

A list of licenses authors might use can be found here

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About the Author

Hojjat Salmasian
Web Developer
United States United States
No Biography provided

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Comments and Discussions

 
QuestionNumeric TextBox in VB.Net Pin
SumitSaha11-Jan-15 15:42
memberSumitSaha11-Jan-15 15:42 
GeneralMy vote of 5 Pin
Pawan.riseup3-Jun-14 22:34
memberPawan.riseup3-Jun-14 22:34 
GeneralMy vote of 1 Pin
Kazna4ey8-Jun-13 6:51
memberKazna4ey8-Jun-13 6:51 
QuestionAdvanced Numeric Pin
Sureshjv11-Dec-12 19:54
memberSureshjv11-Dec-12 19:54 
QuestionHey You can check here Advanced Numeric Text Box http://getvbnetcode.blogspot.in/ Pin
Sureshjv11-Dec-12 19:53
memberSureshjv11-Dec-12 19:53 
GeneralPasted data Pin
iamthecodecutter8-May-11 19:26
memberiamthecodecutter8-May-11 19:26 
GeneralMy vote of 1 Pin
saeed mousavi4-Feb-09 4:54
membersaeed mousavi4-Feb-09 4:54 
GeneralCool and what about positive numbers Pin
SalarSoft11-Jul-07 20:07
memberSalarSoft11-Jul-07 20:07 
Generaldecimal point Pin
torbero11-Jul-07 8:30
membertorbero11-Jul-07 8:30 
GeneralRe: decimal point Pin
Hojjat Salmasian12-Jul-07 4:16
memberHojjat Salmasian12-Jul-07 4:16 
GeneralSmall Issue Pin
MNC6217-Jun-07 21:26
memberMNC6217-Jun-07 21:26 
Thanks for this, very useful but I have a smallish issue.

The example from the downloaded project does not allow you to enter a decimal the format like .xx but instead 0.xx. Small point I know but many users will input a fraction this way when entering large volumes od data.Smile | :)
GeneralFlaw.... Pin
chris1759-Feb-07 7:31
memberchris1759-Feb-07 7:31 
GeneralRe: Flaw.... Pin
Hojjat Salmasian9-Feb-07 9:58
memberHojjat Salmasian9-Feb-07 9:58 
GeneralThank you Pin
PocketJem5-Dec-06 9:49
memberPocketJem5-Dec-06 9:49 
GeneralRe: Thank you Pin
Hojjat Salmasian5-Dec-06 19:06
memberHojjat Salmasian5-Dec-06 19:06 
GeneralRe: Thank you Pin
PocketJem6-Dec-06 8:35
memberPocketJem6-Dec-06 8:35 
GeneralRe: Thank you Pin
Hojjat Salmasian7-Dec-06 6:58
memberHojjat Salmasian7-Dec-06 6:58 
GeneralThe contorl don't support inputing minus symbol. Pin
zxp31922-Feb-06 20:46
memberzxp31922-Feb-06 20:46 
GeneralRe: The contorl don't support inputing minus symbol. Pin
Hojjat Salmasian23-Feb-06 4:35
memberHojjat Salmasian23-Feb-06 4:35 
GeneralRe: The contorl don't support inputing minus symbol. Pin
Ray Cassick25-Feb-06 11:22
memberRay Cassick25-Feb-06 11:22 
GeneralRe: The contorl don't support inputing minus symbol. Pin
Hojjat Salmasian26-Feb-06 6:31
memberHojjat Salmasian26-Feb-06 6:31 
GeneralRe: The contorl don't support inputing minus symbol. Pin
Ray Cassick26-Feb-06 7:12
memberRay Cassick26-Feb-06 7:12 
GeneralRe: The contorl don't support inputing minus symbol. Pin
Hojjat Salmasian27-Feb-06 6:46
memberHojjat Salmasian27-Feb-06 6:46 
GeneralRe: The contorl don't support inputing minus symbol. Pin
LovinBill12-Jul-06 23:56
memberLovinBill12-Jul-06 23:56 
GeneralRe: The contorl don't support inputing minus symbol. Pin
Hojjat Salmasian15-Jul-06 4:06
memberHojjat Salmasian15-Jul-06 4:06 
Questionvs2005 only? Pin
GaryMinor222-Feb-06 10:31
memberGaryMinor222-Feb-06 10:31 
AnswerRe: vs2005 only? Pin
Christian Graus22-Feb-06 10:54
memberChristian Graus22-Feb-06 10:54 
AnswerRe: vs2005 only? Pin
Hojjat Salmasian22-Feb-06 16:08
memberHojjat Salmasian22-Feb-06 16:08 
Questionwhat about coma ? Pin
scalpa9822-Feb-06 0:28
memberscalpa9822-Feb-06 0:28 
AnswerRe: what about coma ? Pin
Hojjat Salmasian22-Feb-06 5:40
memberHojjat Salmasian22-Feb-06 5:40 
GeneralRe: what about coma ? Pin
scalpa9822-Feb-06 6:48
memberscalpa9822-Feb-06 6:48 
GeneralRe: what about coma ? Pin
Hojjat Salmasian22-Feb-06 16:04
memberHojjat Salmasian22-Feb-06 16:04 
GeneralRe: what about coma ? Pin
scalpa9822-Feb-06 19:18
memberscalpa9822-Feb-06 19:18 
GeneralRe: what about coma ? Pin
Hojjat Salmasian23-Feb-06 4:33
memberHojjat Salmasian23-Feb-06 4:33 
AnswerRe: what about coma ? Pin
Rob_III4-Sep-06 5:19
memberRob_III4-Sep-06 5:19 

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