C# WPF how to use value of object sender to clear value in the input-box which has evoked the code-CodePudding

I'm creating a WPF application with a few input-text-fields and input should be checked if it contains only numbers and comma ( = convert to double must be possible) and so I have written the following code

private void txtBarauslagen_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if (e.Key == Key.Return || e.Key == Key.Tab)
    {
        string text = txtBarauslagen.Text;

        if (text != "") // nur wenn Feld nicht leer
        {
            try
            {
                double convtext = double.Parse(text);
                MessageBox.Show(convtext.ToString());
                // txtNotiz_int.Focus();
            }
            catch
            {
                MessageBox.Show("FALSCH - nicht nur Zahlen!");
                txtBarauslagen.Text = ""; 
                e.Handled = e.Key == Key.Tab;
            }
        }
    }
}

The line "e.Handled = e.Key == Key.Tab;" is necessary because I have code in "LostFocus" which should only be executed if "convert to double" is possible.

I'd like to know if it is possible to change the line "txtBarauslagen.Text = "";" so that it is possible to refactor the code so that I can use the same code for another input-text-field. I have tried already to change it to "text.Text" in the catch-statement but that is not possible (I do not really know why).

To put it in a nutshell: I'd like to know if it is possible to retrieve the value for instance "txtBarauslagen.Text" or the object "txtBarauslagen" ( = my input-text-field) from "object sender).

CodePudding user response：

Since the sender is supposed to be the TextBox which raised that event, just cast it to TextBox and you can access its Text property.

TextBox tb = (TextBox)sender;

BTW, if I were you, I will use double.TryParse method instead.

CodePudding user response：

This is the revised code which is functioning properly, thank you

private void zeit1TextBox_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Return || e.Key == Key.Tab)
        {
            TextBox tb = (TextBox)sender;

            string TBSender = tb.Text;
            double standVal = 0;

            if (TBSender != "") // nur wenn Feld nicht leer
            {
                double.TryParse(TBSender, out standVal);

                if (standVal != 0)
                {
                    tb.Text = standVal.ToString();
                }
                else
                {
                    MessageBox.Show("Nur Eingabe von Zahlen möglich!");
                    tb.Text = "";
                    e.Handled = e.Key == Key.Tab; // verhindert dass Focus weiterspringt
                }
            }
        }
    }