写入文本文件：
1 class Program
2 {
3 static void Main(String[] args)
4 {
5 //写入string数组，每个string一行
6 string[] lines = { "first line", "second line ", "third line", "forth line" };
7 System.IO.File.WriteAllLines(@"D:IOTestIOTest1.txt", lines);
8 //写入一个字符串
9 string text = "ahhhhhhhhhhhhhhhhhhhhhhhhhhh";
10 System.IO.File.WriteAllText(@"D:IOTestIOTest2.txt", text);
11 //StreamWriter类，以流的方式写入
12 System.IO.StreamWriter file = new System.IO.StreamWriter(@"D:IOTestIOTest3.txt", true);
13 foreach (var line in lines)
14 {
15 if (!line.Contains("second"))
16 {
17 file.Write(line);
18 file.WriteLine(line);
19 }
20 }
21 file.Flush();
22 file.Close();
23 }
24 }
读取文本文件：
1 class Program
2 {
3 static void Main(String[] args)
4 {
5 //读取为一个字符串
6 string text = System.IO.File.ReadAllText(@"D:iOTESTIOTEST2.TXT");
7 //读取为字符串数组，每行一个字符串
8 string[] lines = System.IO.File.ReadAllLines(@"D:IOTESTIOTEST1.TXT");
9 //StreamReader类，以流的方式读取
10 System.IO.StreamReader sr = new System.IO.StreamReader(@"D:iOTESTIOTEST3.TXT");
11 string str;
12 while ((str = sr.ReadLine()) != null)
13 {
14 Console.WriteLine(str);
15 }
16 sr.Close();
17 }
18 }