Question

I’m making a custom Terminal in a C# winform. When the user presses a key in the TextBox that I’m using I have to make sure that it’s a valid key. I need to prevent them from being able to delete stuff and do whatever they want. I managed to handle the backspace and delete and others via the KeyPress and KeyDown events. I had a problem with the user pressing shift + delete. It deletes stuff just like backspace. I don’t know what the integer equivalent of it is. I made a C++ program to detect it, it was simple:

char c = _getch();
cout << (int)c << endl;

I got a -32. It didn’t work in C#.

After so many tries to encircle its value, I found that it was 0.
It worked, at least for yesterday, but now it doesn’t. I’m also able to delete stuff with the shift+delete.

Here’s my key validation method:

private bool IsInvalidKey(char key)
{
  bool condition1 = !IsAsciiKey(key) && !IsNavigatingKey(key); // by navigation I mean: left, right, end and home keys.
  bool condition2 = (GetCaretPosition() == CaretPosition.OutsideCommandLine && !IsNavigatingKey(key));
  bool condition3 = ((key == (char)Keys.Back) && GetCaretPosition() == CaretPosition.BeginningOfCommandLine);
  return (condition1 || condition2 || condition3);
}

private bool IsAsciiKey(char key)
{
  return ((int)key > 0 && (int)key <= 127); // char(0) should be shift+delete
}

How can I detect this key and where (in which event, KeyPress or KeyDown?)

I’m using a normal TextBox control, not a RichTextBox.

Answer 1

You could try something like this in the KeyDown event.

private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.Shift && e.KeyCode == Keys.Delete) e.Handled = true;
}