Copying one TextBox(Content) to another in RPN Calculator
<pre><code>    I am doing a RPN calculator program in that  I have 4 textboxes and a Enter button when i enter data (say it as 22 ) when i press enter it should goto 2 textbox 
</code></pre>

<p>and when i again enter data and press enter textbox 2 content must be copied to 3 and 1 to 2.. The section of code that i have pasted is for action when i press enter.i am unable to do this please help me out
    fOR MORE INFO ron CALCULATOR SHOULD LOOK LIKE THIS 
        <a href="http://icrank.com/data/calculator/calc_app.htm" rel="nofollow">http://icrank.com/data/calculator/calc_app.htm</a></p>

<pre><code> if (!(textBox1.Text=="") ) // Check whether tB1 is not empty and inserting value
                {
                    Double a = Double.Parse(textBox1.Text);
                    stk.Push(a);
                    textBox2.Text = textBox1.Text;     /// copying values from TB2 to Tb1
                    val= textBox1.Text;
                    //textBox1.Text="";

                }
                 if(!(textBox2.Text == ""))//Check whether tB2 is not empty and inserting value

                {
                    Double a1 = Double.Parse(textBox2.Text);
                    stk.Push(a1);// pushing data on to stack
                    textBox3.Text = textBox2.Text;
                    textBox2.Text = val;
                    textBox1.Text = "";

                }

               if (!(textBox3.Text == ""))// Check whether tB3 is not empty and inserting value
                {
                    Double a2 = Double.Parse(textBox3.Text);

                    stk.Push(a2);// pushing data on to stack
                    textBox4.Text = textBox3.Text;// copying TB3 to TB2
                    textBox3.Text = textBox2.Text;/// copying TB3 to TB2
                    textBox2.Text = val;
                    textBox1.Text = "";
</code></pre>
