Check if String is number or not using C# and VB.Net in ASP.Net

Hi chetan,

Check this sample. now take its reference and correct your code.

HTML

<asp:TextBox ID="txtID" runat="server" /><br /><br />
<asp:Button ID="btnSubmit" Text="Submit" runat="server" OnClick="OnValidate" /><br />
<asp:Label ID="lblID" Text="" runat="server" />

Code

C#

protected void OnValidate(object sender, EventArgs e)
{
    int classID;
    if (!int.TryParse(txtID.Text, out classID))
    {
        ClientScript.RegisterStartupScript(this.GetType(), "", "alert('Please Enter Only Numeric Value.')", true);
    }
    else
    {
        lblID.Text = "MEASUREMENT CLASS ID : " + Convert.ToString(classID);
    }
}

VB.Net

Protected Sub OnValidate(ByVal sender As Object, ByVal e As EventArgs)
    Dim classID As Integer
    If Not Integer.TryParse(txtID.Text, classID) Then
        ClientScript.RegisterStartupScript(Me.[GetType](), "", "alert('Please Enter Only Numeric Value.')", True)
    Else
        lblID.Text = "MEASUREMENT CLASS ID : " & Convert.ToString(classID)
    End If
End Sub

Screenshot