1 #include <iostream>
 2 #include <algorithm>
 3 using namespace std;
 4 struct type_1
 5 {
 6     int a,b;
 7     type_1(int x=0,int y=0):a(x),b(y){}
 8 };
 9 bool compare(type_1 a,type_1 b)
10 {
11     return a.a<b.a;
12 }
13 bool operator < (const type_1 &a,const type_1 &b)
14 {
15     return a.a<b.a;
16 }
17 ostream& operator<<(ostream &cout,const type_1 &a)
18 {
19     cout<<"("<<a.a<<","<<a.b<<")";
20 }
21 int main()
22 {
23     type_1 vec[10]={type_1(3,4),type_1(2,4),type_1(1,4),type_1(9,4),type_1(31,4),type_1(25,4),type_1(2,4),type_1(9,4),type_1(2,4),type_1(1,4)};
24     sort(vec,vec+10);//通过定义小于<
25     for(int i=0;i<10;i++)
26         cout<<vec[i]<<" ";
27         cout<<endl;
28 
29     return 0;
30 }