Question

I would like to modify the default behavior of a regular WinForms C# textbox control so that pressing backspace deletes whole words instead of just a single character.

Ideally I would like to have this special behavior only when the caret position is in-front of a white-space character. For example; pressing backspace one time when the caret is at “hello world|” should still only remove one character resulting in “hello worl|” – but if the caret is at “hello world |” when I press backspace, then the result should be “hello |”

Answer 1

First you need to add KeyEventHandler for KeyDown event for your TextBox

this.textBox1.KeyDown += new System.Windows.Forms.KeyEventHandler(this.textBox1_KeyDown);

After that you can handle the event like this:

        private void textBox1_KeyDown(object sender, KeyEventArgs e)
        {
            TextBox t = (TextBox)sender;
            if (e.KeyCode == Keys.Back)
            {
                int carretIndex = t.SelectionStart;
                if (carretIndex>0 && carretIndex == t.Text.Length && t.Text[carretIndex-1] == ' ')
                {
                    int lastWordIndex = t.Text.Substring(0, t.Text.Length - 1).LastIndexOf(' ');
                    if (lastWordIndex >= 0)
                    {
                        t.Text = t.Text.Remove(lastWordIndex + 1);
                        t.Select(t.Text.Length, 0);
                    }
                    else
                    {
                        t.Text = string.Empty;
                    }
                }
            }
        }