private void sortAlphabetticallyAscending(ListBox listBox)
        {
            string[] s = new string[listBox.Items.Count];
            for (int i = 0; i < listBox.Items.Count; i++)
                s[i] = (string)listBox.Items[i];
            Array.Sort(s);
            listBox.BeginUpdate();
            listBox.Items.Clear();
            for (int i = 0; i < s.Length; i++)
                listBox.Items.Add(s[i]);
            listBox.EndUpdate();
        }

        private void sortAlphabetticallyDescending(ListBox listBox)
        {
            string[] s = new string[listBox.Items.Count];
            for (int i = 0; i < listBox.Items.Count; i++)
                s[i] = (string)listBox.Items[i];
            Array.Sort(s);
            Array.Reverse(s);
            listBox.BeginUpdate();
            listBox.Items.Clear();
            for (int i = 0; i < s.Length; i++)
                listBox.Items.Add(s[i]);
            listBox.EndUpdate();
        }

        private void sortByLengthAscending(ListBox listBox, int l, int r)
        {
            Random random = new Random();
            int i = l, j = r;
            string x = (string)listBox.Items[random.Next(l, r)];
            while (i <= j)
            {
                while (((string)listBox.Items[i]).Length < x.Length)
                    i++;
                while (((string)listBox.Items[j]).Length > x.Length)
                    j--;
                if (i <= j)
                {
                    string temp = (string)listBox.Items[j];
                    listBox.Items[j] = listBox.Items[i];
                    listBox.Items[i] = temp;
                    i++;
                    j--;
                }
            }
            if (l < j)
                sortByLengthAscending(listBox, l, j);
            if (r > i)
                sortByLengthAscending(listBox, i, r);
        }

        private void sortByLengthDescending(ListBox listBox, int l, int r)
        {
            Random random = new Random();
            int i = l, j = r;
            string x = (string)listBox.Items[random.Next(l, r)];
            while (i <= j)
            {
                while (((string)listBox.Items[i]).Length > x.Length)
                    i++;
                while (((string)listBox.Items[j]).Length < x.Length)
                    j--;
                if (i <= j)
                {
                    string temp = (string)listBox.Items[j];
                    listBox.Items[j] = listBox.Items[i];
                    listBox.Items[i] = temp;
                    i++;
                    j--;
                }
            }
            if (l < j)
                sortByLengthDescending(listBox, l, j);
            if (r > i)
                sortByLengthDescending(listBox, i, r);
        }