private void TUTAR_TextChanged(object sender, EventArgs e)
 {
     if (TUTAR.Text != "")
     {
         TUTAR.TextChanged -= new EventHandler(TUTAR_TextChanged);
         if (TUTAR.Text.Contains(","))
         {
             if (OgrenciLib.AfterChr(TUTAR.Text, ',').Length > 2)
             {
                 TUTAR.Text           = tutarLastText;
                 TUTAR.SelectionStart = TUTAR.Text.Length;
                 TUTAR.TextChanged   += new EventHandler(TUTAR_TextChanged);
                 return;
             }
             else if (OgrenciLib.BeforeChr(TUTAR.Text, ',').Length == 0)
             {
                 TUTAR.Text = "0," + OgrenciLib.BeforeChr(TUTAR.Text, ',');
             }
             else
             {
                 double numeric = Convert.ToDouble(OgrenciLib.RemoveChar(OgrenciLib.BeforeChr(TUTAR.Text, ','), '.'));
                 TUTAR.Text = numeric.ToString("#,0") + "," + OgrenciLib.AfterChr(TUTAR.Text, ',');
             }
         }
         else
         {
             double doubleVal = Convert.ToDouble(OgrenciLib.RemoveChar(TUTAR.Text, '.'));
             TUTAR.Text = doubleVal.ToString("#,0");
         }
         tutarLastText        = TUTAR.Text;
         TUTAR.SelectionStart = TUTAR.Text.Length;
         TUTAR.TextChanged   += new EventHandler(TUTAR_TextChanged);
     }
 }