How to avoid more than One Dot(.) symbol in textbox?

Question

How to avoid more than One Dot(.) symbol in text box?

Because In my form (Windows application) all text box contains decimal values..

If I enter double dots . . it rise the error at the time of calculation..

In my form I've 12 text boxes

Vulpes · Answer

Something like this should prevent more than one dot being entered: private void textBox1_KeyPress(object sender KeyPressEventArgs e) { if (e.KeyChar == '.' && textBox1.Text.Contains(.)) { e.Handled = true; } }