统计文本中的单词个数，并按出现次数降序输出（支持大文本）,原版是http://www.oschina.net/code/snippet_176897_7944。采用hash_map,GCC采用#include <ext/hash_map>。修改版本是VS2010采用#include <hash_map>using namespace stdext VC调用hash_map的例子，值得学习。-The number of words in the statistics text, press the number of occurrences of descending output (supports large text), original http://www.oschina.net/code/snippet_176897_7944. Hash_map, GCC# include <ext/hash_map>. The modified version of VS2010# include <hash_map> using namespace stdext　VC use hash_map example, it is worth learning.