c++中vector的pair与make_pair的使用，双关键字排序

#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
bool strict_weak_ordering(const pair<int,string> a, const pair<int,string> b)
{
    return a.first > b.first;
}
//通过运算符重载，利用sort函数实现降序排列
int main()
{
    vector<pair<int, string> > vec;
    //为了避免与>>运算符混淆，所以这里中间要有个空格
    vec.push_back(make_pair<int, string>(5, "bingo"));
    vec.push_back(make_pair<int, string>(4, "bing"));
    vec.push_back(make_pair<int, string>(6, "acbingo"));
    vec.push_back(make_pair<int, string>(6, "ACBingo"));
    vec[3].first++;
    sort(vec.begin(), vec.end(), strict_weak_ordering);
    //使用迭代器
    vector<pair<int, string> >::iterator it = vec.begin(), end = vec.end();
    for (;it!=end;++it) cout<<it->first<<endl;
    //模拟正常数组
    for (int i=0;i<vec.size();i++)  cout<<vec[i].second<<endl;
    return 0;
}