How To Allow Only Numbers In TextBox Control?
Very often developers need to allow only numbers in TextBox control. It can be very easily archived with markup code bellow:
<asp:TextBox
id="txtNumbersOnly"
Runat="server"
/>
<asp:RegularExpressionValidator
Runat="server"
ID="valNumbersOnly"
ControlToValidate="txtNumbersOnly"
Display="Dynamic"
ErrorMessage="Please
enter a numbers only in text box."
ValidationExpression="(^([0-9]*|\d*\d{1}?\d*)$)">
</asp:RegularExpressionValidator>
Important:
You still need to check user input on server side, because malicious user can make POST request without using your web form. You can perform this check by using Regex class. For this case, code would be:
[ C# ]
if
(!Regex.IsMatch(txtNumbersOnly.Text,
@"(^([0-9]*|\d*\d{1}?\d*)$)"))
{
// It is not a number, do something!
}
[ VB.NET ]
If
Not Regex.IsMatch(txtNumbersOnly.Text, _
"^[a-zA-Z'.]{1,40}$")
Then
' It is not a number, do something!
End
If
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1. Security Features in ASP.NET 2.0
2. Save & Read Image From Database
