Retrive number only from a AlphaNumeric string using C#

Hi yohana,

I have created sample code which fullfill requirement.

HTML

<div>
    <asp:TextBox ID="txtNumber" runat="server" />
    <asp:Button Text="Submit" OnClick="Submit" runat="server" />
    <br />
    <asp:Label ID="lblnumbers" Text="" runat="server" />
</div>

C#

protected void Submit(object sender, EventArgs e)
{
    lblnumbers.Text = "";
    string mytext = txtNumber.Text;
    char[] myChars = mytext.ToCharArray();
    foreach (char ch in myChars)
    {
        if (char.IsDigit(ch))
        {
            lblnumbers.Text += ch.ToString();
        }
    }
}

Screenshot

I hope works for you.