ASP.Net - Regular Expression Validator

Here is a sample

<asp:RegularExpressionValidator 
    ID="RegularExpressionValidator1" 
    runat="server"
    ControlToValidate="YourTextBoxID"
    ErrorMessage="Only numeric allowed." 
    ForeColor="Red"
    ValidationExpression="^[0-9]*$" 
    ValidationGroup="NumericValidate">*
</asp:RegularExpressionValidator>

Where

• ValidationExpression - this is a regular expression

More Information

• https://stackoverflow.com/questions/1427629/asp-net-validation-to-make-sure-textbox-has-integer-values