C/C++ 获取系统环境变量方法.

C/C++ 获取系统环境变量方法.

http://www.cnblogs.com/algorithmic/archive/2012/09/23/2698604.html

GetEnvironmentVariable function

http://msdn.microsoft.com/en-us/library/ms683188%28VS.85%29.aspx

GetSystemDirectory function

http://msdn.microsoft.com/en-us/library/ms724373%28v=vs.85%29.aspx