指针函数和函数指针
参考链接:
http://www.cnblogs.com/gmh915/archive/2010/06/11/1756067.html
http://lionwq.spaces.eepw.com.cn/articles/article/item/18258
http://www.programfan.com/blog/article.asp?id=6030
http://hi.baidu.com/bellgrade/item/4a4334e8132eed0965db00a6
http://blog.chinaunix.net/uid-10386087-id-2959230.html
http://c.chinaitlab.com/ccjq/865383.html