使用StreamReader和StreamWriter读取和写入文本文件

1.读取文本文件

using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Collections;
using System.Diagnostics;
using System.IO;
namespace 练习专用
{
    class Program
    {
        static void Main(string[] args)
        {
            using (FileStream fs = new FileStream(@"E:\清理系统盘.txt", FileMode.Open))
            {
                using (StreamReader sr = new StreamReader(fs))
                {
                    //一行一行读取
                    StringBuilder sb = new StringBuilder();
                    while (!sr.EndOfStream)
                    {
                        sb.AppendLine(sr.ReadLine());
                    }
                    Console.WriteLine(sb.ToString());
                    //直接读到末尾
                    //string str = sr.ReadToEnd();
                    //Console.WriteLine(str);
                }
            }
        }
    }
}

2.写入文本文件

using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Collections;
using System.Diagnostics;
using System.IO;
namespace 练习专用
{
    class Program
    {
        static void Main(string[] args)
        {
            using (FileStream fs = new FileStream(@"E:\test.txt", FileMode.OpenOrCreate))
            {
                using (StreamWriter sw=new StreamWriter(fs))
                {
                    string str = "不积跬步，无以至千里；不积小流，无以成江海。";
                    sw.Write(str);
                }
            }
        }
    }
}