关于new和delete
new：先分配内存，再调用ctor -->调用malloc
delete：先调用dtor，再释放内存 -->调用free
#include <iostream>
#include <stdlib.h>
using namespace std;
class Fruit {
public:
Fruit(int _no = 0, double _weight = 0.0, char _key = 'f'):no(_no), weight(_weight), key(_key){
cout << "create fruit instance..." << endl;
}
~Fruit(){
cout << "destroy fruit instance..." << endl;
}
int no;
double weight;
char key;
public:
void print(){}
virtual void process(){}
};
class Apple : public Fruit{
public:
Apple(int _size = 0, char _type = 'a'):size(_size), type(_type){
cout << "create apple instance..." << endl;
}
~Apple(){
cout << "destroy apple instance..." << endl;
}
int size;
char type;
public:
void save(){}
virtual void process(){}
};
inline void* operator new(size_t size){
cout << "global new function" << endl;
return malloc(size);
}
inline void operator delete(void *ptr){
cout << "global delete function" << endl;
return free(ptr);
}
int main(int argc, char ** argv){
cout << "[Test 1] : normal Fruit instance:" << endl;
{
Fruit f;
}
cout << "[Test 2] : normal Apple instance:" << endl;
{
Apple apl;
}
cout << "[Test 3] : global new and delete Fruit instance pointer: " << endl;
{
Fruit *pf = new Fruit();
delete pf;
pf = NULL;
}
cout << "[Test 4] : global new and delete Apple instance pointer:" << endl;
{
Apple *pa = new Apple();
delete pa;
pa = NULL;
}
return 0;
}
执行结果：
Paste_Image.png
重载operator new，operator delete，operator new[] 和 operator delete[]
全局重载：
作为成员函数重载：（常用作内存池的设计）
注：当new，delete， new[] 和delete[]使用全局重载的时候，其范围是整个程序范围内的，其影响深远，应谨慎使用。
