Adding Button Controls Inside Class

Question

I had this problem, I can't add a control inside a class. More specifically the Controls.Add(Button);. Is this possible or do i missing something.

    MyFunctions mf = new MyFunctions();
    class MyFunctions
    {
        public int ButtonWidth(int number)
        {
            string a = "";
            int ButtonWidth=0;

            Button x = new Button();
            x.Size = new Size(10, 40);//Initial Size
            x.AutoSize = true;
            x.AutoSizeMode = AutoSizeMode.GrowAndShrink;
            Controls.Add(x);//Why i can't this one?

            for(int i=1;i<=number;i++)
            {
                a += "X";
                x.Text = a;
                ButtonWidth = x.Width;

                MessageBox.Show(i + "-" + a + "-" + ButtonWidth);
            }
            return ButtonWidth;
        }
  }`

I got an error message.

can't access a non-static member of outer type.

I made a trial to see if the button width is changing when button.text changes its length. but the button.width is held constant.

Ian · Accepted Answer · 2016-03-17 07:29:15Z

1

Your MyFunctions is a separate class from your Form class. And therefore, it does not have Controls property (the Controls property belongs to your Form - or its derived - class)

If you want to add a Button in your Form class, you should make your code block a Method of your Form instead of a new, separated MyFunctions class:

public class MyForm : Form {  
    public int ButtonWidth(int number) //this is OK
    {
        string a = "";
        int ButtonWidth=0;

        Button x = new Button();
        x.Size = new Size(10, 40);//Initial Size
        x.AutoSize = true;
        x.AutoSizeMode = AutoSizeMode.GrowAndShrink;
        Controls.Add(x);//Why i can't this one?

        for(int i=1;i<=number;i++)
        {
            a += "X";
            x.Text = a;
            ButtonWidth = x.Width;

            MessageBox.Show(i + "-" + a + "-" + ButtonWidth);
        }
        return ButtonWidth;
    }
}

That being said, since your method name is to ButtonWidth, it is not advisable (not a good design) to add Button in a method which is meant to get ButtonWidth. Consider separation of Methods: CreateButton to create your Button, GetButtonWidth to get the ButtonWidth (though it may not be necessarily made a method) and then you simply add your created Button to your Form's Controls.

answered Mar 17, 2016 at 7:29

Ian

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1 Comment

Ian Over a year ago

@Vincent great. ;) please note my comment on your code design too... I strongly encourage you to consider separation of Methods to make your code becomes much clearer.

James Decker · Accepted Answer · 2016-03-17 07:32:25Z

0

You're trying to access an instance of a class, from an instance of another class.

Try making MyFunctions static, or include the functions on a base class that the first class derives from.

answered Mar 17, 2016 at 7:32

James Decker

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