C#读写文本文件。解决办法

C#读写文本文件。
我想写个单击butten1把文本文件里的内容读到textbox1中，再单击butten2，把textbox1中的文件写到另一个新建文本里，谢谢了，初学者，不会写，哪位高手能指点下，最好能详细点或给出代码，谢谢了，

[解决办法]
1.你可以直接用File.Move（）方法或者FileInfo 的MoveTo()方法直接移动文件

System.IO操作

C# code

try         {            // Create an instance of StreamReader to read from a file.            // The using statement also closes the StreamReader.            using (StreamReader sr = new StreamReader("TestFile.txt"))             {                String line;                // Read and display lines from the file until the end of                 // the file is reached.                while ((line = sr.ReadLine()) != null)                 {                    Console.WriteLine(line);                }            }        }        catch (Exception e)         {            // Let the user know what went wrong.            Console.WriteLine("The file could not be read:");            Console.WriteLine(e.Message);        }
[解决办法]
读:TextBox1.Text=File.ReadAllText("d:/b.txt",Encoding.Default);

写:File.WriteAllText("d:/a.txt", TextBox1.Text, Encoding.Default);
[解决办法]
追加:File.AppendAllText("d:/a.txt", TextBox1.Text, Encoding.Default);