Mask with Regex and replace to allow single digits and a single hyphen

Question

What I need:

A mask that works in the event keypress of a TextBox replacing what is not numerical and excessive hyphens with "".

What is my difficulty:

Check the entry of only one hyphen in the same expression.

I arrived at the solution using substring and only worked on KeyUP, but wanted to arrive through an expression.

What I’ve already tried:

using System.Text.RegularExpressions;

private static Regex digitsOnly = new Regex(@"(:?[^\d\-])");


private void inputSequencial_KeyUp(object sender, KeyEventArgs e)
{
   if (!String.IsNullOrEmpty(inputSequencial.Text)
   {
      inputSequencial.Text = digitsOnly.Replace(inputSequencial.Text, "");

      //MatchCollection matches = Regex.Matches(inputSequencial.Text, "[\\-]");
      //
      //if (matches.Count > 1)
      //{
      //    for (int i = 1; i <= matches.Count - 1; i++)
      //    {
      //         inputSequencial.Text = inputSequencial.Text.Substring(0, matches[i].Index-1) + inputSequencial.Text.Substring(matches[i].Index, inputSequencial.Text.Length);
      //         inputSequencial.Text = inputSequencial.Text.Replace(inputSequencial.Text[matches[i].Index].ToString(), "");
      //    }
      //}
   }
}

Expected result:

If you know a better way to do that, please point me out. Thank you for your attention.

Answer 1

I researched here some alternatives, with Regex or Maskedtextbox(This did not help me much because by default it is not accepted in toolStrip where my textbox was).

In the end the best solution I found was treating the input values to each character as follows:

private void inputSequencial_KeyPress(object sender, KeyPressEventArgs e)
{
   //So permite a entrada de digitos(char 48 à 57), hífen (char 45), backspace(char 8) e delete(char 127)
   if ((e.KeyChar >= 48 && e.KeyChar <= 57) || e.KeyChar == 45 || e.KeyChar == 8 || e.KeyChar == 127)
   {    
      switch (e.KeyChar)
      {
         case (char)45:
         int count = inputSequencial.Text.Split('-').Length - 1;
         //Se for o primeiro caracter digitado no input ou 
         //se já existir um hífen evito a inserção.
         if (inputSequencial.Text.Length == 0 || count > 0)
         {
            e.Handled = true;
         }
         break;
      }
   }
   else
   {
      e.Handled = true; //Desprezo outras entradas
   }
}

private void inputSequencial_KeyUp(object sender, KeyEventArgs e)
{
   //Se o ultimo caracter for um hífen eu removo ele.
   if (inputSequencial.Text.Length > 1)
   {
      string lastChar = inputSequencial.Text.Substring(inputSequencial.Text.Length - 1, 1);
      if (lastChar == "-")
      {
         inputSequencial.Text.Replace("-", "");
      }
   }
}