C#中txt文件的读取和写入

C# winform的程序内用openfiledialog来打开对话框选择文件， 用savefiledialog来打开对话框显示要存储的文件名和文件路径

程序代码如下：

    private void button2_Click(object sender, EventArgs e)
    {
        OpenFileDialog ofldg = new OpenFileDialog();
        ofldg.Title = "选择需要打开的文件";
        ofldg.Filter = "Txt(*.txt)|*.txt";
        ofldg.InitialDirectory = @"D:\";
        if (ofldg.ShowDialog() == DialogResult.OK)
        {
            string filename = ofldg.FileName;
            textBox2.Text = filename;
            try
            {
                // 创建一个 StreamReader 的实例来读取文件 
                // using 语句也能关闭 StreamReader
                StreamReader streamReader = new StreamReader(filename);
                //判断文件中是否有字符
                while (streamReader.Peek() != -1)
                {
                    //读取文件中的一行字符
                    string str = streamReader.ReadToEnd();
                    textBox1.Text = str ;
 
 
                }
                streamReader.Close();
 
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
    }
 
    private void button1_Click(object sender, EventArgs e)
    {
        SaveFileDialog sflg = new SaveFileDialog();
        sflg.Filter = "Txt(*.txt)|*.txt";
        if(sflg.ShowDialog() == DialogResult.OK)
        {
            textBox2.Text = sflg.FileName;
            StreamWriter swriter = new StreamWriter(sflg.FileName, true);
            swriter.Write(textBox1.Text);
        }
    }