how to pass string or value from usercontrol to main form in C#
<p>I created a usercontrol that contains many buttons and in the main form I have a textbox. 
I add the usercontrol to the main form and I want to click any button on the usercontrol and have the textbox in the main form shows the button text.
The question is how to pass the string of the button in usercontrol to the textbox in the main form? <a href="http://i.stack.imgur.com/Bgkw4.png" rel="nofollow">This is what I'm trying to do </a></p>

<pre><code>public partial class UserControl1 : UserControl
{
    public UserControl1()
    {
        InitializeComponent();

    }
    public string a ;




    private void button1_Click(object sender, EventArgs e)
    {
        a = button1.Text;
    }

    private void button2_Click(object sender, EventArgs e)
    {
        a = button2.Text;
    }

    private void button3_Click(object sender, EventArgs e)
    {
        a = button3.Text;


    }
</code></pre>

<p>and the main form code is :</p>

<pre><code> private void textBox1_TextChanged(object sender, EventArgs e)
    {
        textBox1.Text = usrCtrl.a;
        // usrCtrl come from : Usercontrol1 usrCtrl = new Usercontrol1();
    }
</code></pre>

<p>and it shows nothing in the textbox.</p>