How to get old text and changed text of textbox on TextChanged event of textbox?

Question

I am fairly new to c#. I have requirement of previous text and newly changed text of text box on text changed event of the same. I tried to get text on textchanged event but it is new text only. How can I get previous text also?

e.g. Say I have a text "abc" in my text box and I change it to "pqr" by pasting text directly and not by typing. now on text change event txtbox.text returns me "pqr" . But I need to compare previous and new text , so I need "abc" also. So how can I get it?

private void txtFinalTrans_TextChanged_1(object sender, EventArgs e)
{
    gstrOldText = txtFinalTrans.Text;              
}

Answer 1

Try creating a global variable and put your textbox text during GotFocus event and use it as Old Text during TextChanged event as like:

string OldText = string.Empty;
private void textBox1_GotFocus(object sender, EventArgs e)
{
   OldText = textBox1.Text;
}

private void textBox1_TextChanged(object sender, EventArgs e)
{
   string newText = textBox1.Text;
   //Compare OldText and newText here
}

Hope this helps...