https://blog.csdn.net/lethic/article/details/7781203

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

typedef struct example
{
    int elem1;
    int elem2;
}example;

/*这个comparison函数很重要.如果希望升序排序,就是"<",降序排列就是">"号,这样便于直观记忆.如果希望用elem2作为比较标准
就把elem1改为elem2,这样结构体就以elem2为比较标准排序了.*/ bool comparison(example a,example b){
    return a.elem1<b.elem1;
}

int main()
{
    int N;
    fin>>N;

    vector<example> array(N);

    for(int i=0;i<N;i++)
    {
        fin>>array[i].elem1>>array[i].elem2;
    }

    sort(array.begin(),array.end(),comparison);

    for(int i=0;i<N;i++)
    {
        cout<<array[i].elem1<<" "<<array[i].elem2<<endl;
    }
        return 0;
}
***********************************************************************
 [http://www.bubuko.com/infodetail-3443696.html](https://) 
重写仿函数（函数指针法）
#include<iostream>
#include<algorithm>
using namespace std;

struct stu{
    int num;
    float score;
}; 

bool cmp(const stu &a, const stu &b){
    return a.score < b.score;
}

int main(){
    stu nums[3] = {{1,98.5}, {2,88.5}, {3,68.5}};
    sort(nums, nums + 3, cmp);
    for(int i = 0; i < 3; ++ i)
    {
        cout << nums[i].score <<endl;
    }
    return 0;
}
重载运算符（struct内部 + struct外部）
#include<iostream>
#include<algorithm>
using namespace std;

struct stu{
    int num;
    float score;
    bool operator<(const stu &a) const
    {
        return score < a.score;
    }
}; 

int main(){
    stu nums[3] = {{1,98.5}, {2,88.5}, {3,68.5}};
    sort(nums, nums + 3);
    for(int i = 0; i < 3; ++ i)
    {
        cout << nums[i].score <<endl;
    }
    return 0;
}
#include<iostream>
#include<algorithm>
using namespace std;

struct stu{
    int num;
    float score;
}; 

bool operator<(const stu &a, const stu &b)
{
    return a.score < b.score;
}

int main(){
    stu nums[3] = {{1,98.5}, {2,88.5}, {3,68.5}};
    sort(nums, nums + 3);
    for(int i = 0; i < 3; ++ i)
    {
        cout << nums[i].score <<endl;
    }
    return 0;
}