my if statement within my switch statement does not work correct within my calculator. need help fixing the divide by 0 error

Question

i created a basic calculator, but with division i coded it, that when i divide by zero it will give the error to the user in the 2nd textbox, but now even if i divide by 3 or an

Answer 1

On the first line of aequal_Click(object sender, RoutedEventArgs e) replace

Double num02 = 0;

by

Double num02 = Convert.ToDouble(textbox1.Text);