Question

I put a generic list in a private helper method…

    private void addButton()
    {
        List<Button> buttonList = new List<Button>();

        buttonList.Add(button1);
        buttonList.Add(button2);
        buttonList.Add(button3);
        buttonList.Add(button4);
        buttonList.Add(button5);
        buttonList.Add(button6);
        buttonList.Add(button7);
        buttonList.Add(button8);
        buttonList.Add(button9); 
    }

I know to call this method you have to do something like this…

    private void button1_Click(object sender, EventArgs e)
    {
            addButton();

            foreach (button in addButton())
            {
                button.Enabled = false;
            }
    }

however… when I try to call button in addButton() red lines appear underneath ‘button’ saying that it could not be found. Please can someone help 🙂

Answer 1

Your method should return the list:

private List<Button> addButton()
{
    List<Button> buttonList = new List<Button>();

    buttonList.Add(button1);
    //...
    return buttonList;
}

Also you don’t need the first addButton();:

private void button1_Click(object sender, EventArgs e)
{
        foreach (Button button in addButton())
        {
            button.Enabled = false;
        }
}

And I would have this method rewritten with yield keyword:

private IEnumerable<Button> addButton()
{
    yield return button1;
    yield return button2;
    //...
    yield return button9;
}

as you do not need to create a list of buttons just to go through them each time you need to. It’s enough just to enumerate them.

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Also review Methods (C# Programming Guide), section about methods returning values:

Methods can return a value to the caller. If the return type, the type
listed before the method name, is not void, then the method can return
the value using the return keyword. A statement with the keyword
return followed by a value that matches the return type will return
that value to the method caller. The return keyword also stops the
execution of the method. If the return type is void, a return
statement with no value is still useful to stop the execution of the
method. Without the return keyword, the method will stop executing
when it reaches the end of the code block. Methods with a non-void
return type are required to use the return keyword to return a value.

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P.S.: review my answer in How do I shorten this generic list?. Probably this would still be a better approach?