[Solved] Textbox don’t allow typing ” \ ” 2 times after each other [duplicate]

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a textreplace isn’t working in my case. i need an error shown up when a user leaves the box when he types more then one \

If this is what you really want you need to use a ErrorProvider. Add one to your form then add the following code to the texbox’s Validating event and be sure that CausesValidation is true for the textbox

private void textBox1_Validating(object sender, CancelEventArgs e)
{
    if(Regex.IsMatch(textBox1.Text, @"\\\\+"))
    {
        e.Cancel = true;
        errorProvider1.SetError(textbox1, @"\\ Is not allowed");
    }
    else
    {
        errorProvider1.SetError(textbox1, null);
    }
}

This will make a ! show up next to the text box if they type wrong and force them to correct it when they attempt to leave the text box.

solved Textbox don’t allow typing ” \ ” 2 times after each other [duplicate]