单文档多视图SdiMulti_demo，在VC单文档架构中实现多文档界面-Single document multi-view SdiMulti_demo, in the framework of VC single document multi-document interface

MFC中，编写单文档界面程序，当用户用鼠标单击程序窗口用户区时，在当前目录下，一只写方式创建一个名为“myfile.txt”的文件，并向其写入字符“hello，this is a file”-MFC, write a single document interface program, when the program window with the mouse click the user area, in the current directory, a write mode create