How to limit the texbox to accept only numbers and backspace? - asp.net

Question

I have to create a textbox which will ignore all the non numeric input.
I tried to use this code which I found in this site
Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
e.Handled = Not Char.IsDigit(e.Keychar)
End Sub
But I have a mistake in this part of the code System.Windows.Forms.KeyPressEventArgs
What am I doing wrong?

Answer 1

hope this helps
Sub btnDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles MyBase.KeyPress
if e.KeyChar= Chr(8)
'do something for backspace
else if e.KeyChar=(CHr(13)
'do something for enter
end if
end sub

Answer 2

I agree with Dai
Key stroke in ASP.net SHOULD ALWAYS be managed on the client side to avoid unecessary postback an avoid overloading server .
If you are not familiar with Javascript you can refer to this excelleent tutorial from W3School to manage the onChangeEvent of an input
http://www.w3schools.com/jsref/event_onchange.asp
If you really want to manage the key 'on fly', you can manage the 'onkeyDown' event
http://www.w3schools.com/jsref/event_onkeydown.asp

Answer 3

Use this in code-behind
if(Regex.IsMatch(yourStringToValidate,"^[a-zA-Z0-9\\\$]+$")
{
//Place your msg
}
else
{
//Place your validation msg
}

Answer 4

Try using the MaskedTextBox and set the mask to some thing like this:
maskedTextBox1.Mask = "\d*";

Answer 5

This code should be placed within head section of html.
I have used Jquery library to validate purpose
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$('#mytext').keydown(function(e) {
if (e.shiftKey) e.preventDefault();
else {
var nKeyCode = e.keyCode;
//Ignore Backspace and Tab keys
if (nKeyCode == 8 || nKeyCode == 9) return;
if (nKeyCode < 95) {
if (nKeyCode < 48 || nKeyCode > 57) e.preventDefault();
} else {
if (nKeyCode < 96 || nKeyCode > 105) e.preventDefault();
}
}
});
});
</script>
Html code
<input type="text" id="mytext">