C#使用StreamReader类和StreamWriter类读写文本文件

StreamReader类和StreamWriter类可以实现读写文本文件，这两个类都在命名空间System.IO下。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WinFormStream
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnWriter_Click(object sender, EventArgs e)
        {
            using (StreamWriter streamWriter = new StreamWriter("test.txt"))
            {
                for (int i = 1; i <= 10; i++)
                {
                    streamWriter.WriteLine(i + ":" + DateTime.Now.ToString() + " \r\n");
                }
            }
            MessageBox.Show("文件写入成功！");
        }

        private void btnReader_Click(object sender, EventArgs e)
        {
            try
            {
                if (!File.Exists("test.txt"))
                {
                    MessageBox.Show("test.txt文件不存在");
                }
                using (StreamReader streamReader = new StreamReader("test.txt"))
                {
                    string line;
                    StringBuilder stringBuilder = new StringBuilder();
                    while ((line = streamReader.ReadLine()) != null)
                    {
                        stringBuilder.Append(line);
                    }
                    MessageBox.Show(stringBuilder.ToString());
                }
            } catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
    }
}