Один обработчик события для нескольких TextBox'ов

string tmp = textbox1.Text.Trim();
string outS = string.Empty;
bool z_1 = true;
if(tmp.Lenght > 1 && tmp[0] == '0' && tmp[1] !=',')
tmp = tmp.Substring(1);
foreach(char ch in tmp)
if (Char.IsDigit(ch) || (ch == ',' && z_1))
{
outS +=ch;
if (ch ==',')
z_1 = false;
}
textbox1.Text = outS;
textbox1.SelectionStart = outS.Lengh;

private void textBox_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar == '.')
    {
        e.KeyChar = ','; 
    }
 
    if ((e.KeyChar == ',' && textBox1.Text.Contains(',')) | (!char.IsDigit(e.KeyChar) && e.KeyChar != (char)8 && e.KeyChar != ','))
    {
        e.Handled = true;
    }
}

private void textBox_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar == '.')
    {
        e.KeyChar = ',';
    }
 
    if ((e.KeyChar == ',' && (sender as TextBox).Text.Contains(',')) | (!char.IsDigit(e.KeyChar) && e.KeyChar != (char)8 && e.KeyChar != ','))
    {
        e.Handled = true;
    }
}

private void textBox_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar == '.')
    {
        e.KeyChar = ',';
    }
    if (char.IsDigit(e.KeyChar) && (sender as TextBox).Text == "0")
    {
        (sender as TextBox).Text = e.KeyChar.ToString();
        e.Handled = true;
        (sender as TextBox).Select(1, 0);
    }
 
    if ((e.KeyChar == ',' && (sender as TextBox).Text.Contains(',')) 
        | (!char.IsDigit(e.KeyChar) && e.KeyChar != (char)8 && e.KeyChar != ','))
    {
        e.Handled = true;
    }
}