一、自定义比较函数

#include <iostream>
#include <algorithm>
using namespace std;
struct Node{
	string name;
	int age;
};

bool cmp(const Node a, const Node b)
{
	return a.age < b.age; // < 就是前面的小于后面的，即从小到大排序 
}

int main()
{
	struct Node nodes[3];
	nodes[0].name = "zhang";
	nodes[0].age = 18;
	
	nodes[1].name = "wang";
	nodes[1].age = 20;
	
	nodes[2].name = "li";
	nodes[2].age = 19;
	
	
	sort(nodes, nodes + 3, cmp);
	
	
	for(int i = 0; i < 3; ++i) {
		cout << nodes[i].age << endl;
	}
} 

二、结构体内嵌比较函数

#include <iostream>
#include <algorithm>
using namespace std;
struct Node{
	string name;
	int age;
	
	// 这里是cpp的运算符重载，重载了 <  
	bool operator < (const Node& a) const
	{
		return age < a.age;  // < 就是从小到大排序 
	} 
};


int main()
{
	struct Node nodes[3];
	nodes[0].name = "zhang";
	nodes[0].age = 18;
	
	nodes[1].name = "wang";
	nodes[1].age = 20;
	
	
	nodes[2].name = "li";
	nodes[2].age = 19;
	
	
	sort(nodes, nodes + 3);
	
	
	for(int i = 0; i < 3; ++i) {
		cout << nodes[i].age << endl;
	}
}