|for cases where you must handle entry of groups of characters that do not map to the many
Is---- methods provided by Char, you may need to test if the char is in a specific group of characters:
private string legalChars = "()+-*/";
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
char c = e.KeyChar;
e.Handled = !
«One day it will have to be officially admitted that what we have christened reality is an even greater illusion than the world of dreams.» Salvador Dali