说明：  这是一个控制Autocad命令输入行的小程序，可以取得Autocad的命令，也可以输入并执行命令，采用API方式，没有用传统的COM方式，也是一个DEMO，希望对大家有用!
(This is a control command input line Autocad small program, you can get Autocad command, you can enter and execute the command, the use of API methods, COM did not use the traditional way, is a DEMO, we hope to be useful!)