STL sort实现可迭代容器中对象的多重标准排序

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

 using namespace std;

 class Cat{
 public:
     int id;
     string name;
     int age;
     Cat(int i,string n,int a){
         id = i;
         name =n;
         age = a;

     }
 };

 /*
 实现自己的比较函数：
 格式：
     bool compName(Obj1, Obj2);
 注意：
 1. 函数必须返回bool值
 2. 函数如果返回true就表示该参数或者标准按这种顺序排序(即不用swap)，返回false即会swap
 3. 函数作为sort(beginIndex,endIndex,compName)的第三个参数;

 */
 bool myCompare(Cat *a,Cat* b){
     //先按id从小到大排序
     if(a->id<b->id)return true;
     else if(a->id>b->id)return false;
     else {
         //id相同
         //按name的字典序排序
         if(a->name.compare(b->name)<)return true;
         else if(a->name.compare(b->name)>)return false;
         else{
             //name相同，按age从小到大排序
             if(a->age<b->age)return true;
             if(a->age>b->age)return false;
             else{
                 //age也相同
                 //返回true
                 return true;
             }
         }

     }
 }

 int main(){
     vector<Cat*> v ;
     v.push_back(new Cat(,"Jim",));
     v.push_back(new Cat(,"Jima",));
     v.push_back(new Cat(,"Jimb",));
     v.push_back(new Cat(,"Jimc",));
     v.push_back(new Cat(,"J",));
     v.push_back(new Cat(,"Jim",));
     v.push_back(new Cat(,"Jizzz",));
     v.push_back(new Cat(,"Jim",));
     v.push_back(new Cat(,"Jim",));
     sort(begin(v),end(v),myCompare);
     for(int i=;i<v.size();i++){
         Cat * c = v[i];
         cout<<c->id<<" "<<c->name<<" "<<c->age<<endl;
     }

 }

 /*
 output:
 1 J 1
 1 Jim 1
 1 Jima 1
 1 Jimb 1
 1 Jimc 1
 2 Jim 1
 2 Jim 2
 2 Jim 3
 2 Jizzz 1

 */