新运算符和删除运算符重载

Question

任何人都可以解释以下程序中发生的情况

// CPP program to demonstrate  
// Overloading new and delete operator  
// for a specific class 
#include<iostream> 
#include<stdlib.h> 

using namespace std; 
class student 
{ 
    string name; 
    int age; 
public: 
    student() 
    { 
     cout<< "Constructor is called\n" ;  
    } 
    student(string name, int age) 
    { 
        this->name = name; 
        this->age = age; 
    } 
    void display() 
    { 
        cout<< "Name:" << name << endl; 
        cout<< "Age:" << age << endl; 
    } 
    void * operator new(size_t size) 
    { 
        cout<< "Overloading new operator with size: " << size << endl; 
        void * p = ::new student();  
        //void * p = malloc(size); will also work fine 

       return p; 
    } 

    void operator delete(void * p) 
    { 
        cout<< "Overloading delete operator " << endl; 
        free(p); 
    } 
    }; 

int main() 
{ 
 student * p = new student("Yash", 24); 

 p->display(); 
    delete p; 
} 

重载new运算符有什么用，在我对上述程序的理解中，重载的new运算符仍在使用malloc分配内存，而无需重载new运算符就可以了吗？

如果我错了，请纠正我。

谢谢！