Doing text input only in a KeyPress event

Question

I have a keystroke event and I want the combobox to handle the keystroke if the input is not text. I.E. If it is an up or down key, let the combobox handle it as usual, but if it is punctuated or alphanumeric, I want to act on it.

I thought that Char.IsControl (e.KeyChar)) would do the trick, but it won’t catch the arrow keys for combobox, which is important.

Answer 1

Here is an example from the previous answer I gave. It came from the MSDN documentation, and I think you should modify it well based on which characters you want to allow or deny:

// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;

// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    // Initialize the flag to false.
    nonNumberEntered = false;

    // Determine whether the keystroke is a number from the top of the keyboard.
    if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
    {
        // Determine whether the keystroke is a number from the keypad.
        if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
        {
            // Determine whether the keystroke is a backspace.
            if(e.KeyCode != Keys.Back)
            {
                // A non-numerical keystroke was pressed.
                // Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = true;
            }
        }
    }
    //If shift key was pressed, it not a number.
    if (Control.ModifierKeys == Keys.Shift) {
        nonNumberEntered = true;
    }
}

// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
    // Check for the flag being set in the KeyDown event.
    if (nonNumberEntered == true)
    {
        // Stop the character from being entered into the control since it is non-numerical.
        e.Handled = true;
    }
}

Answer 2

You do not need to check for text characters.

Hope the following code helps:

void ComboBox_KeyPress(object sender, KeyPressEventArgs e)
{
    if(Char.IsNumber(e.KeyChar))
        ...
    else if(Char.IsLetter(e.KeyChar))
        ...
}