C# textbox deletion question

Question

Hi:

I am working on a project that I use textbox as telnet terminal. The terminal has "->" as the command prompt in the textbox. Is there a way to disable the delete or backspace once it reach the "->" prompt?

I don't want to delete the command prompt.

Thanks

Answer 1

Two options:

1. Make the prompt ("->") an image or label, instead of being part of the textbox.
2. If it's a web app, handle the textchanged event in javascript and cancel the textchanged if it represents a deletion of the prompt. If its not a web app, do the same thing in c# rather than JS.

Answer 2

Dave is right.

The best way to do this is to make a label on the left side of the textbox that says ->. You can remove the textbox's border and put them both in a white (or non-white) box to make it look real.

This will be much easier for you to develop and maintain, and will also be more user-friendly. (For example, the Home key will behave better)

Answer 3

You could always make sure that when deleting, the index of the character you're deleting is > 1 (since -> would occupy positions 0 & 1)

Answer 4

This is a naive example, but you should be able to figure it out from here. You can peak at the keydown event and cancel it, when desired.

private void testTextBox_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Back && testTextBox.SelectionStart == 2)
    {
        e.SuppressKeyPress = true;
    }
}