richTextBox3.Text = "";
            if (richTextBox1.Text == "" || richTextBox2.Text == "")
            {
                richTextBox3.Text = "请在两列中输入数据,否则无法进行合并";
            }
            else
            {
                int a = richTextBox1.Lines.Length;
                int b = richTextBox2.Lines.Length;
                List<string> i = new List<string>();
                for (int c = 0; c < a; c++)
                    for (int d = 0; d < b; d++)
                        if (richTextBox1.Lines[c] != richTextBox2.Lines[d])
                        {
                            if (!i.Contains(richTextBox1.Lines[c]))
                                i.Add(richTextBox1.Lines[c]);
                            if (!i.Contains(richTextBox2.Lines[d]))
                                i.Add(richTextBox2.Lines[d]);
                        }
                foreach (string j in i)
                    richTextBox3.Text += j + "\r\n";
                string f = richTextBox3.Text;
                int g = richTextBox3.Lines.GetUpperBound(0);
                richTextBox3.Text += "合并后有" + (Convert.ToString(g)) + "个数据";合并的速度也非常慢。有没有什么解决办法呢?