C++ new delete new[] delete[]重载实现

这篇博文主要是分析了C++ new（）和构造函数的执行，delete()与析构函数的调用方式，通过全局重载和局部重载看清楚调用的关系

using namespace std;#include <iostream>#include <cstdlib>class Student{public:Student(){cout <<  "Constructer" << endl;}~Student(){cout << "析构函数" << endl;}static void* operator new(size_t size){cout << "own new function" << endl;Student* stu = (Student*)::operator new(size);return stu;}static void operator delete(void* p){cout << "own delete function" << endl;::delete p;}static void* operator new[](size_t size){cout <<  "own new[] function" <<endl;return ::operator new(size);}   };void* operator new(size_t size){cout << "global new function" << endl;void* p = malloc(size);return p;}void operator delete(void * p){cout << "global delete function"<< endl;free(p);}void operator delete[](void* p){cout << "global delete[] function" << endl;free(p);}void main(){Student* student = new Student();delete student;//Student* student2 = new Student[5];//delete[] student2;cin.get();}

可以看出执行顺序为:内部重载的new-->全局重载的new()--->malloc()-->构造函数初始化-->内部的析构函数---》内部的delete()--》全局的delete()-->free()函数

可以看出重载new[]和delete[]先执行malloc()分配所需要的内存然后每个元素会调用构造函数进行初始化