返回文件指定行的字符串！！！问题高手快啊 ！！！！

Question

 public void button2_Click(object sender, EventArgs e)
        {
            string i = textBox1.Text;
            
            double userGuess = Int32.Parse(textBox1.Text);
            Random rnd = new Random();
            double Number = rnd.NextDouble() * Convert.ToDouble(i);
            
            Number = Math.Round(Number);
            string str = "随机出现的数字是" + Number + "," + "您输入的数字是" + userGuess + "\n";
            label2.Text = str;
            openFileDialog1.InitialDirectory = ("E:\\");
            openFileDialog1.Filter = "文本文件(*.txt)|*.txt|Word文件(.doc)|*.doc|所有文件(*.*)|*.*";
            DialogResult r = openFileDialog1.ShowDialog();
            ArrayList array = new ArrayList();
            
            if (r == DialogResult.OK)
            {
                StreamReader sr = new StreamReader(openFileDialog1.FileName);
                string sd = sr.ReadLine();
                int s=Number
                for ()
                {
                                    }
高手看下 
随机数Number
打开一个文件 返回到TextBox.text上随机数Number的相应文件行的字符串！！！！
                

Answer 1

把行读到arrayList里面，然后通过arraylist找相应的行

Answer 2

        string GetLineString(string fileName, Encoding encoding, int index)
        {
            if (index < 0) return null;
            StreamReader sr = new StreamReader(fileName, encoding);
            string[] strs = sr.ReadToEnd().Split(new string[] { Environment.NewLine }, StringSplitOptions.None);
            sr.Close();
            if (index >= strs.Length) return null;
            return strs[index];
        }        private void Form1_Load(object sender, EventArgs e)
        {
            Console.WriteLine(GetLineString("D:\\123.txt", Encoding.Default, 222));
        }