Virtual number pad in C#- Is there an elegant way to update Textbox.SelectionStart?

Question

I am designing a virtual number pad in Windows Form. Please suppose that I have Del key to remove character of textbox. When I click on the textbox for the first time to select it and then press the Del key, the character is removed correctly relative to cursor position. But after updating the content of text, the SelectionStart property changes to zero and my blinking cursor disappeared. I solved this problem by saving its value temporarily before updating the content of textbox and modifying it at the end.

tempSelectionStart = enteredTextbox.SelectionStart; //save SelectionStart value temporarily 
enteredTextbox.Text = enteredTextbox.Text.Substring(0, enteredTextbox.SelectionStart - 1)
                    + enteredTextbox.Text.Substring(enteredTextbox.SelectionStart,
                      enteredTextbox.Text.Length - (enteredTextbox.SelectionStart));
enteredTextbox.SelectionStart = tempSelectionStart-1;

I want to know:

Is there a more elegant way to solve the problem?
How can I hold cursor blinking in the textbox after first time I pressed the key?

Thanks.

Hans Passant · Accepted Answer · 2015-09-01T11:53:56.030

2

Use the SelectedText property instead:

private void DeleteButton_Click(object sender, EventArgs e) {
    if (textBox1.SelectionLength == 0) textBox1.SelectionLength = 1;
    textBox1.SelectedText = "";
    textBox1.Focus();
}

private void BackspaceButton_Click(object sender, EventArgs e) {
    if (textBox1.SelectionLength == 0) {
        if (textBox1.SelectionStart > 0) {
            textBox1.SelectionStart--;
            textBox1.SelectionLength = 1;
        }
    }
    textBox1.SelectedText = "";
    textBox1.Focus();
}

edited Sep 01 '15 at 11:53

answered Sep 01 '15 at 11:25

Hans Passant

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If you want the Del key works as Backspace and delete the character which is placed left side of cursor , only substract one from `SelectionStart`. Is there another way? – IndustProg Sep 01 '15 at 11:54
2

Sigh. You still use the SelectionText property. – Hans Passant Sep 01 '15 at 11:55
Dear Passant , can you please guide me to do it by SelectedText property? – IndustProg Sep 01 '15 at 11:58
I posted the code, no idea what else you could possibly want. – Hans Passant Sep 01 '15 at 11:59
Dear Passant, I am grateful of you. – IndustProg Sep 01 '15 at 12:03

Virtual number pad in C#- Is there an elegant way to update Textbox.SelectionStart?

1 Answers1