如何测试Ctrl键？

Question

I can't get the Ctrl key state in the KeyUp event handler as the Ctrl key is released.

Do I have to test the keycode of the event argument?

Is there any other way?

Answer 1

Wiring an event to the KeyUp event handler will work.

The following code will trigger when the Ctrl key is released:

private void Form1_KeyUp(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.ControlKey)
    {
        MessageBox.Show("Control key up");
    }
}

If you want to test if the Ctrl was pressed in combination with another keystroke, for example: Ctrl + F1 then the following code snippet might apply:

private void Form1_KeyUp(object sender, KeyEventArgs e)
{
    if (e.Control && e.KeyCode == Keys.F1)
    {
        MessageBox.Show("Control + F1 key up");
    }
}

Side note: You might have to enable KeyPreview on the form in order to catch all control KeyUp events in a single location.

Answer 2

private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    if(e.Modifiers == Keys.Control)
     ...
}