An object reference is required for the non-static field, method, or property

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Hi,

I'm getting the following error :

Error 1 An object reference is required for the non-static field, method, or property 'TstProject.frmMain.myvar' C:\DISK_C\CSharp\__tmp\tstproject\tstproject\OneClass.cs 10 12 TstProject

with this code :

frmMain:

C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace TstProject
{
	public partial class frmMain : Form
	{
		// non-static field
		public int zozo;

		public frmMain()
		{
			InitializeComponent();
		}

		private void frmMain_Load(object sender, EventArgs e)
		{
			myvar = 100;

			OneClass oc = new OneClass();
		}
	}
}

OneClass :

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TstProject
{
	class OneClass
	{
		public OneClass()
		{
			int zz = frmMain.myvar;

			zz *= 2;
		}
	}
}

I would like to get the value set in frmMain inside the class OneClass ! how can I do that ?

thanks in advance,
sincerly,
Domi.

Posted 29-Mar-12 2:10am

Wrangly

Updated 29-Mar-12 2:35am

v3

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Comments

Shahin Khorshidnia 29-Mar-12 8:56am

If you have any question about the solutions, please comment under the aolution.
Do not ask your new question as a new solution. It wont be answered and will be deleted by editors.

3 solutions

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Shahin Khorshidnia · Answer 1 · 2012-03-29T02:39:00

Use a Constructor for the class.

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TstProject
{
    class OneClass(int myVar)
    {
        int zz = myVar;
    }
}

and in the Form:

C#

//...
private void frmMain_Load(object sender, EventArgs e)
{
    //myvar = 100;

    OneClass oc = new OneClass(100);
}
//...

But some marginal notes:
1. What is myval? It hasn't been defined.
2. You don't need to use a static variable for this case.
3. What is your plan for zozo?
4. your notation is not standard, for example:
frmMain is in hungarian notation that you should not use.
myvar(?!) what notation does it have? if it's a field or a variable use myVar (camelCasing) and if it's a propertym use MyVar (PascalCasing).

Please look at C# Coding Standards - and Naming Conventions

sjelen · Answer 2 · 2012-03-29T02:26:00

Solution 2

Declaring 'myvar' as public static will solve the error:

C#

public partial class frmMain : Form
{
    public static int myvar = 100;
...

Posted 29-Mar-12 2:26am

sjelen

bbirajdar · Answer 3 · 2012-03-29T02:18:00

Solution 1

Whatever you are doing, i.e. accessing the private variable defined in the frmMain into another class is wrong approach. Since it is private it is not accessible.

The best way would be to define it as a property in the OneClass.

Posted 29-Mar-12 2:18am

bbirajdar