What is the difference between these three ways to clear a Textbox?

Question

I am bit confused between the below three ways to clear the contents of a textbox. I am working with WPF and found All are working, but I am unable to find the difference.

Answer 1

Let's go through the commands one by one.

txtUserName.Clear();

The Clear() command assigns the texbox an empty string just like the next example. Source (best explination is given by syned on this point)

txtUserName.Text = string.Empty;

Now the string.Empty the actuall code for it is

static String()
{
    Empty = "";
}

Meaning that you assign the string "" after compile time.

txtUserName.Text = "";

Now here you just assign the "" string directly to the object on compile time.

Small side note txtUserName.Text = ""; is faster than txtUserName.Text = string.Empty; Source