C++重载new delete

#include <iostream>
#include <cstdlib>
using namespace std;
class Foo{
    private:
        int _id;
    public:
        Foo(int id):_id(id){
            cout<<"Foo(int id) id:"<<id<<endl;
        }
        Foo():_id(0){
            
        };
    static void*  operator new(size_t size){
        void *ptr;
        cout<<"new size:"<<size<<endl;        
        ptr = malloc(size);
        cout<<"new ptr:"<<ptr<<endl;
        return ptr;
       }
    static void* operator new[] (size_t size){
          cout<<"new [] size:"<<size<<endl;
          return malloc(size);
      }
    static void operator delete (void *ptr, size_t size){
        cout<<"delete size:"<<size<<endl;
        cout<<"delete ptr:"<<ptr<<endl;
        free(ptr);
    }
    static void operator delete [](void *ptr, size_t size){
        cout<<"delete [] size :"<<size<<endl;
        free(ptr);
    }
};
int main(){
    
    Foo *p = new Foo(2);
    delete p;
    cout<<"------------------"<<endl;
    Foo* ptr = new Foo[3];
    delete []ptr;
    cout<<endl;
    return 0;
}

输出:
new size:4
new ptr:0x315a0
Foo(int id) id:2
delete size:4
delete ptr:0x315a0
------------------
new [] size:16
delete [] size :16