向文本中读写文本和数据

1.向文本中写入文本

下面的示例可向文本现有的文件中添加文本

 　　　  string path = @"....TestFile.Text";
            using (StreamWriter sw = new StreamWriter(path))
            {
                sw.Write("This is the ");
                sw.WriteLine("header for the file.");
                sw.WriteLine("-------------------------");
                sw.Write("The date is:");
                sw.WriteLine(DateTime.Now);
            }

运行后程序在指定路径的文件夹中建立一个文本文件TestFIle.txt,文本内容为：

This is the header for the file.
-------------------------
The date is:2014/3/12 17:37:52

下面的示例创建一个新文本文件并向其中写入一个字符串。WriteAllTest方法可提供类似的功能：

　　  private const string FILE_NAME = @"....MyFile.txt";
        static void Main(string[] args)
        {
            if (File.Exists(FILE_NAME))
            {
                Console.WriteLine("{0}already exists.",FILE_NAME);               
                return;
            }
            using (StreamWriter sw = File.CreateText(FILE_NAME))
            {
                sw.WriteLine("This is my file");
                sw.WriteLine("I can write ints{0} of floats{1},and so on.",1,4.2);
            }
        }

运行后程序在项目文件夹建立一个文本文件MyFile.txt,文件内容为：

This is my file
I can write ints1 of floats4.2,and so on.

2.从文本读取文本

　　下面的代码示例演示如何从文本文件中读取文本。第二个实例在检测到文件结尾时发出通知。

 　　　　try
            {
                string path = @"....TestFile.txt";
                using(StreamReader sr=new StreamReader(path))
                {
                    string line;
                    //读和显示文本的行，直到文件结束
                    //while((line=sr.ReadLine())!=null)

                    line = sr.ReadToEnd();
                        Console.WriteLine(line);                                
                }
            }
            catch(Exception e)
            {
                Console.WriteLine("The file could not be read:");
                Console.WriteLine(e.Message);
            }

下面的示例在检测到文件结尾时发出通知。

 　　 private const string FILE_NALE = @"....MyFile.txt";
        static void Main(string[] args)
        {
            if (!File.Exists(FILE_NALE))
            {
                Console.WriteLine("{0}does not exist.",FILE_NALE);
                return;
            }
            using (StreamReader sr = File.OpenText(FILE_NALE))
            {
                string input;
                while ((input = sr.ReadLine()) != null)
                    Console.WriteLine(input);
                Console.WriteLine("The end fo the stream has been reached");
                Console.ReadKey();
            }

　　上面的代码通过调用File.OpenText创建一个指向MyFile.txt的StreamReader。StreamReader.ReadLine将每一行都作为一个字符串返回。当不再要读取的字段时，会有一条消息显示该情况，然后流关闭