说明：  C#简单读写文件，具体来说是使用StringCollection 类对TXT文本文件的操作，可向TXT中写入文字内容，读取出内容，程序做成了可视化界面，类似一个文本编辑器一样，比Windows的记事本功能还要少一些，主要是演示如何用C#读写文本格式的文件。
(C# is simple to read and write files, specifically using StringCollection class action on TXT text files can be written to the text in TXT, read out the contents, the program made ​ ​ a visual interface, similar to a text editor, than Windows the notepad function even less, mainly demonstrates how to use C# to read and write files in text format.)