10.重载示例（上）

来源：互联网发布：网络数据库类型有哪些编辑：程序博客网时间：2024/06/05 17:35

#include <iostream>#include <stdlib.h>using namespace std;class Foo {public:int _id;long _data;string _str;public:Foo():_id(0) {cout << "default ctor. this=" << this << " id=" << _id << endl; }Foo(int i):_id(i) {cout << "ctor. this=" << this << " id=" << _id << endl; }//non virtual ~Foo() {cout << "dtor. this=" << this << " id=" << _id << endl;}static void* operator new(size_t size);static void operator delete(void* pdead, size_t size);static void* operator new[](size_t size);static void operator delete[](void* pdead, size_t size);};void* Foo::operator new(size_t size){Foo* p = (Foo*)malloc(size);cout << "Foo::operator new(), size= " << size << endl;return p;}void Foo::operator delete(void* pdead, size_t size){cout << "Foo::operator delete(), pdead= " << pdead << " size= " << size << endl;free(pdead);}void* Foo::operator new[](size_t size){Foo* p = (Foo*)malloc(size);cout << "Foo::operator new[](), size= " << size << endl;return p;}void Foo::operator delete[](void* pdead, size_t size){cout << "Foo::operator delete[](), pdead= " << pdead << " size= " << size << endl;free(pdead);}int main() {cout << "sizeof(string) " << sizeof(string) << endl;cout << "sizeof(Foo) " << sizeof(Foo) << endl;Foo* p = new Foo(7);delete p;cout << endl;Foo* pArray = new Foo[5];delete []pArray;cout << "---------------------------------------------------" << endl;p = ::new Foo(7);::delete p;cout << endl;    pArray = ::new Foo[5];::delete []pArray;return 0;}

Foo* p = new Foo(7);

delete p;

Foo* pArray = new Foo[5];

delete []pArray; 若无members 就调用 globals

p = ::new Foo(7);

::delete p;
pArray = ::new Foo[5];
::delete []pArray; 这样调用（也就是写上global scope operator::会逃过前面所有overloaded functions强迫使用global version）

都没有进入重载的operator new(),operator delete(),operator new[](),operato[]()

阅读全文

0 0