How to validate special characters

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<asp:Button ID="ButtonOk" runat="server" Text="OK" OnClick="ButtonOk_Click" />

<br /><br />
<asp:Label ID="Label5" runat="server"></asp:Label>

Write the code on button click where you want to check validateion. First  add the following namespace.

using
System.Text.RegularExpressions;

protected void ButtonOk_Click(object sender, EventArgs e)

{

    if (Regex.IsMatch(TextBox1.Text, @"^[a-zA-Z0-9\s.\?\,\'\;\:\!\-]+$"))

    {

        Label5.Text = "Ok Fine!";

    }

    else

    {

        Label5.Text = "Special Characters are not allowed";

    }

}