Try to catch error when converting text value to number : Exception « Development « ASP.NET Tutorial
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<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="TryCatch" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Try...Catch Example</title>
</head>
<body>
<form id="form1" runat="server">
<div id="container">
<h1>Simple Calculator</h1>
<div class="box">
<asp:TextBox ID="txtValue" runat="server" />
<br />
<asp:Button Text="Do Math" runat="server" ID="btnDivide"
OnClick="btnDivide_Click" />
</div>
<asp:Label ID="labMessage" runat="server" />
</div>
</form>
</body>
</html>
File: Default.aspx.cs
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class TryCatch : System.Web.UI.Page
{
protected void btnDivide_Click(object sender, EventArgs e)
{
try
{
double dVal = Convert.ToDouble(txtValue.Text);
double result = dVal * 100.0;
labMessage.Text = txtValue.Text + "* 100.0";
labMessage.Text += "=" + result;
}
catch (FormatException ex1)
{
labMessage.Text = "Please enter a valid number";
}
catch (Exception ex2)
{
labMessage.Text = "Unable to compute a value with these values";
}
}
}