Clears text only when got focus

Question

  private static void Txb_GotFocus(object sender, EventArgs e)
        {
            var txb = (TextBox)sender;
            var intfc = (ICustomTextBox)sender;
            if (txb.Parent != null)
            {
                OriginalBackColors[txb] = txb.Parent.BackColor;
                txb.BackColor = intfc.FocusBackColor;
                if (!string.IsNullOrEmpty(txb.Text))
                {
                    txb.Select(0, 0);
                   
                }
            }
        }

in the above event i want to add a check that if the textbox got focus and it has some data , the cursor should be at very first position . at the same time , i also want that in the same case (if the textbox got focus and it has some data ) , when the user starts typing in it , all the subsequent text should be cleared . so for example

if the textbox has data = "pankaj" ,when it gets focus again and the cursor gets at before p . so now when he starts typing for example he types N , then pankaj should gets clears out .

  private static void Txb_TextChanged(object sender, EventArgs e)
        {
            var txb = (TextBox)sender;
            var intfc = (ICustomTextBox)sender;
          
                if (intfc.UseUpper && txb.TextLength > 0)
                {
                    string prevText = txb.Text;
                    string nextText = ToUseUpper(prevText);
                    if (nextText != prevText)
                    {
                        int selectionStart = txb.SelectionStart;
                        int selectionLength = txb.SelectionLength;
                        txb.Text = nextText;
                        txb.Select(selectionStart, selectionLength);
                    }
                }
            
        }

Answer 1

Hi @Pankaj tripathi , Welcome to Microsoft Q&A,

I tested using tab to get focus, but you may need to change it if you want to use the mouse to enter focus.

You have too much code, I looked at the requirements in your question.

Wrote the following example using enter and keypress events:

private void textBox1_Enter(object sender, EventArgs e)
{
    var txb = (System.Windows.Forms.TextBox)sender;
    if (!string.IsNullOrEmpty(txb.Text))
    {
        txb.Select(0, 0);
    }
}
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    var txb = (TextBox)sender;
    int cursorPosition = txb.SelectionStart;

    // If the cursorPosition is 0 and the pressed key is a letter, number, symbol key, +-*/ or space bar, clear the content in the TextBox and then enter
    if (cursorPosition == 0 && (char.IsLetterOrDigit(e.KeyChar) || char.IsSymbol(e.KeyChar) || e.KeyChar == '+' || e.KeyChar == '-' || e.KeyChar == '*' || e.KeyChar == '/' || e.KeyChar == ' '))
    {
        txb.Clear();
    }
}

Best Regards,

Jiale

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