How to prevent entering letters in a textbox in asp.net

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I have a textbox in a asp form and I want only to input numbers and "."
And I want to create a session to save in it the text in the text box to use it in another page
Thank you for your help

Posted 18-May-11 13:28pm

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Sergey Alexandrovich Kryukov · Answer 1 · 2011-05-18T13:32:00

You should do it in Javascript as the event needed for this is too frequent, too costly to do it through the server.

Look at this sample:

JavaScript

<html>
   <head>
      <script type="text/javascript"><!--
         function filterDigits(eventInstance) { 
            eventInstance = eventInstance || window.event;
                key = eventInstance.keyCode || eventInstance.which;
            if ((47 < key) && (key < 58) || key = 45 || key == 8) {
               return true;
            } else {
                    if (eventInstance.preventDefault) eventInstance.preventDefault();
                    eventInstance.returnValue = false;
                    return false;
                } //if
         } //filterDigits
      --></script>
   </head>
<body">

<input type="text" onkeypress="filterDigits(event)"/>

</body>
</html>

It does exactly this: allows digits and '.' but also a backspace. By some historical reasons, backspace is processed as a character, not as a raw keyboard event, so it should be allowed separately.

—SA

**Dalek Dave** · Answer 2 · 2011-05-18T13:36:00

Solution 2

The Archive[^] may help.

IsNumeric is probably the best way to go though.
See Here[^]

Hope they help.

Mark up if they do!

Posted 18-May-11 13:36pm

Dalek Dave

saxenaabhi6 · Answer 3 · 2011-05-18T13:56:00

lots of ways to do that
1) from javacript
2) via jquery
3) using ajax control kit validators

or simply use compare validatior in asp (use double as a type in your case)

C#

<br />
<asp:comparevalidator operator="DataTypeCheck" type="Double" controltovalidate="MyTextBox" display="None" errormessage="Valid Number is required." runat="server" /><br />

redirect to another page using text box value as a query parameter like:

C#

<br />
Response.Redirect("~/yourPage.aspx?value=" + MyTextBox.Text);<br />

OR
store it in a session on server side like below:

C#

<br />
Session["TBValue"] = MyTexyBox.Text;<br />

How to prevent entering letters in a textbox in asp.net

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