C#实现写入与读出文本文件的实例代码

写入文本文件

class writetextfile
    {
        static void main()
        {
            //如果文件不存在，则创建；存在则覆盖
            //该方法写入字符数组换行显示
            string[] lines = { "first line", "second line", "third line","第四行" };
            system.io.file.writealllines(@"c:\testdir\test.txt", lines, encoding.utf8);
            //如果文件不存在，则创建；存在则覆盖
            string strtest = "该例子测试一个字符串写入文本文件。";
            system.io.file.writealltext(@"c:\testdir\test1.txt", strtest, encoding.utf8);
            //在将文本写入文件前，处理文本行
            //streamwriter一个参数默认覆盖
            //streamwriter第二个参数为false覆盖现有文件，为true则把文本追加到文件末尾
            using (system.io.streamwriter file = new system.io.streamwriter(@"c:\testdir\test2.txt",true))
            {
                foreach (string line in lines)
                {
                    if (!line.contains("second"))
                    {
                        file.write(line);//直接追加文件末尾，不换行
                        file.writeline(line);// 直接追加文件末尾，换行  
                    }
                }
            }
        }
    }

读取文本文件

class readtextfile
    {
        static void main()
        {
            //直接读取出字符串
            string text = system.io.file.readalltext(@"c:\testdir\test1.txt");
            console.writeline(text);
            //按行读取为字符串数组
            string[] lines = system.io.file.readalllines(@"c:\testdir\test.txt");
            foreach (string line in lines)
            {
                console.writeline(line);
            }
            //从头到尾以流的方式读出文本文件
            //该方法会一行一行读出文本
            using (system.io.streamreader sr = new system.io.streamreader(@"c:\testdir\test.txt"))
            {
                string str;
                while ((str = sr.readline()) != null)
                {
                    console.writeline(str);
                }
            }
            console.read();
        }
    }