如果文本框为空，如何用文本填充文本框？

Question

I use a TextChanged-EventHandler I wrote a program in c# that creates a new TextBox on every button1_Click event Now,I want each new TextBox (which was created) to show typed text. How can I do this with EventHandler(TextChanged)?

namespace WindowsFormsApplication5
{
    public partial class Form1 : Form
    {
        Int32 i = 1;

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        TextBox c = new TextBox();
        this.Controls.Add(c);
        c.Name = "x" + i.ToString();
        c.Left = 3;
        c.Top = 30 * i;
        i++;
        c.TextChanged += new EventHandler(c_TextChanged);


    }

    void c_TextChanged(object sender, EventArgs e)
    {
        textBox1.Text =           
    }

}
}

Answer 1

void c_TextChanged(object sender, EventArgs e)
{
    textBox1.Text = ((TextBox)sender).Text;
}

Answer 2

the sender of your object should be the textbox. There you can get the text you want:

void c_TextChanged(object sender, EventArgs e)
{
    TextBox box = sender as TextBox;
    if (box != null)
    {
        textBox1.Text = box.Text;
    }
}