Sort elements in range
Sorts the elements in the range [first,last) into ascending order.
The elements are compared using operator< for the first version, and comp for the second.
Equivalent elements are not guaranteed to keep their original relative order (see stable_sort).
调用sort，引用头文件：#include <algorithm>
调用less（从小到大），greater（从大到小），引用头文件：#include <functional>
同时对于char等类型排序也是可以的。
基础-Sort函数
原文：http://www.cnblogs.com/ArronXing/p/4634597.html
