读取、写入、生成txt文本文档详解——C#学习笔记

一、4中写入文本的方式：

  //①表示清空 txt
  StreamWriter mytxt1 = new StreamWriter("D:\\1清空.txt");
  string t1 = "";
  mytxt1.Write(t1);
  mytxt1.Close();
  //②表示向txt写入文本
  StreamWriter mytxt2 = new StreamWriter("D:\\2写入覆盖.txt");
  string t2 = "已写入覆盖";
  mytxt2.Write(t2);
  mytxt2.Close();

或

//字符串写入文本,若文件存在则覆盖文件
System.IO.File.WriteAllText(@"C:\Users\Administrator\Desktop\写入新建文本文档.txt", text);
  //③表示追加文本
  StreamWriter mytxt3 = File.AppendText("D:\\3追加.txt");
  string t3 = "追加文字";
  mytxt3.Write(t3);
  mytxt3.Close();
  //④表示追加一行文本并换行
  StreamWriter mytxt4 = File.AppendText("D:\\4追加换行.txt");
  string t4 = "追加换行";
  mytxt4.WriteLine(t4);
  mytxt4.Close();

二、读取文本的方式

 ①将txt文件当成一个对象

StreamReader mytxt2 = new StreamReader("D:\\2写入覆盖.txt"); 

mytxt2.ReadToEnd//读取所有字符到结尾

 mytxt2.ReadLine();  //读取文本中的一行

按行读取内容可通过while(读取行不为空)依次取出。

System.IO.StreamReader file =new System.IO.StreamReader(@"d:\4追加换行.txt");
while ((line = file.ReadLine()) != null)
{System.Console.WriteLine(line);counter++;
}file.Close();

②txt的路径作为一个字符串参数，File对象调用方法的一个参数，通过此方法返回字符串。

// 读取所有文本内容。Read the file as one string.
string text = System.IO.File.ReadAllText(@"C:\Users\Administrator\Desktop\新建文本文档.txt");

下图可知，已读取文本文件所有内容，并赋值给字符串text。

③读取文本内容放入数组中

string[] lines = System.IO.File.ReadAllLines(@"C:\Users\Administrator\Desktop\新建文本文档2.txt");

string[] lines = System.IO.File.ReadAllLines(@"C:\Users\Administrator\Desktop\新建文本文档2.txt");

下图可知，读取文本文件所有内容并放入lines字符串数组中，共54个item(0-53)（行）。

逐个读取数组中文本，可用for each 语句

StreamWriter mytxt4 = File.AppendText("D:\\4追加换行.txt");

 foreach (string line in lines)
 {

     mytxt4.WriteLine(line);

}

StreamWriter mytxt4 = File.AppendText("D:\\4追加换行.txt");foreach (string line in lines){mytxt4.WriteLine(line);}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace ConsoleApp0905
{static class Mytext { static void Main(){//①表示清空 txtStreamWriter mytxt1 = new StreamWriter("D:\\1清空.txt");string t1 = "";mytxt1.Write(t1);mytxt1.Close();//②表示向txt写入文本StreamWriter mytxt2 = new StreamWriter("D:\\2写入覆盖.txt");string t2 = "已写入覆盖";mytxt2.Write(t2);mytxt2.Close();//③表示追加文本StreamWriter mytxt3 = File.AppendText("D:\\3追加.txt");string t3 = "追加文字";mytxt3.Write(t3);mytxt3.Close();//④表示追加一行文本并换行StreamWriter mytxt4 = File.AppendText("D:\\4追加换行.txt");string t4 = "追加换行";mytxt4.WriteLine(t4);mytxt4.Close();System.Console.ReadKey();}}
}

以下为调试代码：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace ConsoleApp0905
{static class Mytext { static void Main(){// The files used here were created in the code example// in How to: Write to a Text File. You can of course substitute// other files of your own.// Example #1// 读取所有文本内容。Read the file as one string.string text = System.IO.File.ReadAllText(@"C:\Users\Administrator\Desktop\新建文本文档.txt");StreamWriter mytxt1 = new StreamWriter("D:\\1清空.txt");// Display the file contents to the console.System.Console.WriteLine("Contents of writeText.txt = {0}", text);//字符串写入文本,若文件存在则覆盖文件System.IO.File.WriteAllText(@"C:\Users\Administrator\Desktop\写入新建文本文档.txt", text);// 按行读取文本，存在字符串数组中。Read the file lines into a string array.string[] lines = System.IO.File.ReadAllLines(@"C:\Users\Administrator\Desktop\新建文本文档2.txt");System.Console.WriteLine("Contents of writeLines2.txt =:");StreamWriter mytxt4 = File.AppendText("D:\\4追加换行.txt");foreach (string line in lines){mytxt4.WriteLine(line);//    }//using (System.IO.StreamWriter filew = new System.IO.StreamWriter(@"C:\Users\Administrator\Desktop\写入新建文本文档2.txt"))//{ //    foreach (string line in lines)//    {//    //"\t"水平制表符//     Console.WriteLine("\t" +line );//        //这个也会覆盖原始文件//     filew.WriteLine(line);//    }}// Keep the console window open in debug mode.Console.WriteLine("Press any key to exit.");System.Console.ReadKey();}}
}