#ifdef预编译相关用法

#ifdef预编译相关用法主要有：
(1)#ifdef XXX
executing the corresponding xxx code
#endif
(2)#ifdef XXX
executing the corresponding xxx code
#else
executing the other code
(3)#ifdef XXX
executing the corresponding xxx code
#elifdef YYY
executing the corresponding yyy code
#else
executing the other code
#endif
注意最后要使用#endif结束

#ifdef预编译相关用法

原文：http://www.cnblogs.com/gjianw217/p/4196368.html