Wrong use of int

ryanburnett · September 8th, 2010, 12:32 PM

Hi, I decided to go back over beg asp.net before going onto pro, and I ran into a wall when I got to the caluclator in class files. Chaper 5. My calculator is in its class file all fine and dandy with Add and Stubtract methods. When I use it in code behind I get the error:

Use of unassigned local variable 'name'

Here is the code:

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        Person myPerson = new Person();
        if(Label2.Text.Length > 0 && Label3.Text.Length > 0)
        {
            int a = Convert.ToInt32(Label2.Text);
            int b = Convert.ToInt32(Label3.Text);
            int myResult;
            switch(DDL1.SelectedValue)
            {
                case "+":
                    myResult = myPerson.Add(a, b);
                    break;
                case "-":
                    myResult = myPerson.Subtract(a, b);
                    break;
            }
            Label1.Text = myResult.ToString();
        }
    }
}

Hope you can help. Thanks . ryan

chroniclemaster1 · September 8th, 2010, 12:51 PM

It literally thinks you're trying to use a variable "name" without assigning a value to it. Since that doesn't appear in this code, it must be an issue in the code which this depends on. If custom errors are off (I recommend using them in production to throw generic errors, but even there you can turn them off in your web.config for a short amount of time to do testing. That will give you the file and line number where "it" thinks the problem is, and it's usually simple to track things down from there. If you can get us that snippet, we should be able to help. I usually start just by copying the error, stack trace, and file as a block for these kinds of problems when I ask for help.

ryanburnett · September 8th, 2010, 01:54 PM

Hi, sorry

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

/// <summary>
/// Summary description for Class1
/// </summary>
public class Person {
    public int Add(int a, int b)
    {
        return a + b;
    }

    public int Subtract(int a, int b)
    {
        return a - b;
    }
}

Thanks again!

Imar · September 9th, 2010, 03:15 AM

Hi ryanburnett,

In the second code snippet you posted, I still see no variable called name.

Maybe the error comes from somewhere else? Where do you get this error exactly? Do you see it in Visual Studio's Error List? If so, double-click the error to go to the file / line where the error occurs.

Cheers,

Imar

ryanburnett · September 9th, 2010, 01:58 PM

Hey, sorry for slow reply I was at school!

I have re-coded the calculator now and here is what I have:

~/Default.aspx

Code:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!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></title>
<style type="text/css">
    body { font-family: Arial; font-size: 12px; color: #000000; }
    .error { background: #8C1D2D; display: block; padding: 3px 5px 3px 5px; color: #FFFFFF; border: 1px solid #C2B5C7; }
    .output { font-size: 34px; font-family: Calibri; }
</style>
</head>
<body>
<form id="form1" runat="server">
<!-- Calculator -->
   <!-- Gather User Input -->
   <div>
    <asp:TextBox ID="IntOne" runat="server" />
        <asp:DropDownList ID="Operator" AutoPostBack="true" runat="server">
            <asp:ListItem>+</asp:ListItem>
            <asp:ListItem>-</asp:ListItem>
        </asp:DropDownList>
    <asp:TextBox ID="IntTwo" runat="server" />
   <!-- End of Gather User Input -->

   <!-- Execute User Input -->
    <asp:Button ID="Execute" Text="Calculate" OnClick="Execute_Click" runat="server" />
   </div>
   <!-- End of Execute User Input -->

   <!-- Output Result -->
   <div>
    <asp:Label ID="Output" CssClass="output" runat="server" />
    <asp:Label ID="OutputError" Visible="false" Text="Error! Please enter two valid intergers!" CssClass="error" runat="server" />
   </div>
   <!--- End of Output Result -->
<!-- End of Calculator --> 
</form>
</body>
</html>

~/Default.aspx.cs

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
 protected void Page_Load(object sender, EventArgs e)
  {
    
  }

 protected void Execute_Click(object sender, EventArgs e)
  {
      if (IntOne.Text.Length > 0 && IntTwo.Text.Length > 0) // execute code if the text boxes are not empty
      {
          int valueOne = Convert.ToInt32(IntOne.Text); // interger to hold the value of the first text box
          int valueTwo = Convert.ToInt32(IntTwo.Text); // interger to hold the value of the second text box
          int outputResult = 0; // interger to hold the value of the result 
          Calculator myCalculator = new Calculator();

          switch (Operator.SelectedValue) 
          {
              case "+":
                  outputResult = myCalculator.Add(valueOne, valueTwo);
                  break;
              case "-":
                  outputResult = myCalculator.Add(valueOne, valueTwo);
                  break;
          }

          Output.Text = outputResult.ToString(); // show output in output textbox
      }
      else
      {
          OutputError.Visible = true; // if nothing is entered show error box
          Output.Visible = false; // and hide the output box
      }
  }
}

~/App_Code/Calculator.cs

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

/// <summary>
/// Provide with two intergers and it will provide basic calculatons on them.
/// </summary>
public class Calculator
{
 public int Add(int a, int b)
 {
    return a + b;
 }

 public int Subtract(int a, int b)
 {
    return a - b;
 }

 public Calculator()
 {
    //
    // TODO: Add constructor logic here
    //
 }
}

web.config

Code:

<?xml version="1.0"?>

<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->

<configuration>

    <system.web>
        <compilation debug="false" targetFramework="4.0" />
    </system.web>

</configuration>

I did it in a blank site so thats all thats in it!

Sorry, after all of that it works... YAY! I belive the problem was me being a dumb ass and not initializing the interger (32) that stored the answer with 0. So its all fine and dandy now! I'm just going to make a fake youtube to test my skills and see if I'm able to progress onto ASP.net pro in C# and VB.net.

Is it me or is the VB.net syntax stupid? Also what host do you use?

Thanks again guys and the brilliant Imar!

Imar · September 10th, 2010, 04:00 AM

Quote:

YAY! I belive the problem was me being a dumb ass and not initializing the interger (32) that stored the answer with 0.

That certainly makes sense. Since it's possible that the switch block doesn't assign a valid value (e.g. you pass none of the supported operators), the result never gets a value. Assigning a default value fixes the warning. I think you out us in the wrong direction by saying that "name" was not given a value.

Quote:

Is it me or is the VB.net syntax stupid?

It's a matter of personal preference. It's not stupid, it's just slightly different. Knowing how to code in both languages is always very useful.

Quote:

Also what host do you use?

I host all of my sites myself.

Quote:

Thanks again guys and the brilliant Imar!

Thank you and you're welcome....

Imar