Simple Int.Parse addition

Question

I'm giving int input in Textbox1 and Textbox2, then the sum of both will be display on Label1. Can anyone show me how it work??? My int.parse not working.

.asxp

 <div>
         <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
         <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
         <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
         <asp:Button ID="Button1" runat="server" Text="Display" />

     </div>

.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace MQM_System
{   
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }
        protected void Button1_Click(object sender, System.EventArgs e)
        {
            int sum = 0;

            sum = int.Parse(TextBox1.Text) + int.Parse(TextBox2.Text);
            Label1.Text = sum.ToString();
        }
    }
}

Answer 1

You must assign Button1_Click event handler to Button event OnClick .

<asp:Button ID="Button1" runat="server" Text="Display" OnClick="Button1_Click" />

Also you should use TryParse method ( msdn ) instead of Parse method in Button1_Click event handler.

Answer 2

The problem with Int.Parse is that it requires a valid number otherwise it raises an exception.
You could use TryParse that allows for better control

  int num1;
  if(!Int32.TryParse(TextBox1.Text, out num1))
  {
      Label1.Text = "Not a valid number";
      return;
  }
  int num2;

  if(!Int32.TryParse(TextBox2.Text, out num2))
  {
      Label1.Text = "Not a valid number";
      return;
  }
  sum = num1 + num2;
  Label1.Text = sum.ToString();