CODEWITHSUNDEEP
c#ooppublicaccess-modifiers
sarahHH
sarahHH

Reputation: 191

Invalid expression term 'public'

For the following code 

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button3_Click(object sender, EventArgs e)
    {
        public int x = 5;
        MessageBox.Show(x.ToString());
    }
}

I have the following error

Invalid expression term 'public'

on the line public int x = 5;

Why can't I define public objects inside event handler?

Upvotes: 0

Views: 1715

Answers (1)

AGB
AGB

Reputation: 2226

public is an access modifier for types (e.g. public class Foo) and type members (such as methods, properties, or fields on a class, e.g. button3_Click).

You are trying to declare a local variable inside a method as public, which is not allowed.

One way to fix the compilation error is to remove the access modifier from the local variable declaration in button3_Click: int x = 5; instead of public int x = 5;. You should use this if you only need to access the variable x within button3_Click and you are happy to have a new variable instantiated for every time button3_Click is called.

Another way to fix the compilation error is to change x from a local variable to a field. By changing where x is defined, you can declare it as a field on Form1 instead of a local variable in the button3_Click scope.

Try:

public partial class Form1 : Form
{
    public int x;

    public Form1()
    {
        InitializeComponent();
    }

    private void button3_Click(object sender, EventArgs e)
    {
        x = 5;
        MessageBox.Show(x.ToString());
    }
}

This option is preferable if you need to access the x field from other methods in your program, or you want to preserve values across multiple invocations of the button3_Click method on the Form1 instance.

If these are the case, you could also decide to make x a property instead of a field in order to gain more fine-grained control over reading, writing, and/or computation of x.

Upvotes: 2

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