[size=large]先貼上參考資料的網址：[/size]
1、[url]http://www.builder.com.cn/2008/0104/696370.shtml[/url]
2、[url]http://c.chinaitlab.com/basic/783582_2.html[/url]

[size=large]感覺自己用的話不需要過載new運算子，畢竟都是要分配記憶體，呼叫建構函式。。自己做記憶體管理直接申請一塊大記憶體用placement new建立物件就好了。
另外，明白了delete與delete[] 的區別在於delete[]回收記憶體前還會逐個呼叫解構函式，因而對於簡單型別等無需析構的兩者沒啥區別。[/size]

#pragma  once
#include "iostream"
//#include <new.h>

using namespace std;

class A
{
public:
	int a;
	int* pInt;
	A(){
		pInt=new int[10];
	}


	A(int a):a(a){
		pInt=new int[10];
	}

	~A(){
		cout<<"A的解構函式！！a="<<a<<";\tpInt="<<(long long)pInt<<endl;
		if(pInt!=NULL)
		{
				delete[] pInt;
				pInt=NULL;
		}
	}


// 	void* operator new(size_t size)
// 	{
// 		cout<<"operator new called"<<endl;;
// 		return ::operator new(size);
// 	}

// 	void* operator new(size_t /*省略名稱以防編譯器警告*/,void* location=(void*)0){//placement new ,如 new(p) A(3); //p->A::A(3);   //必須#include <new>
// 		cout<<"placement new called"<<endl;
// 		return location;
// 	}

};

// void* operator new(size_t size)
// {
// 	cout<<"global new"<<endl;
// 	return malloc(size);
// }


void main(){
	//A* a = new A();
	A a(1);

	char* s=new char[sizeof(A)];
	A* p = (A*)s;
	cout<<"before 'new(p) A(2);' p->a =  "<<p->a<<";\tpInt="<<(long long)p->pInt<<endl;
	new(p) A(2); //p->A::A(2);  //placement new!!!!!!!!!!
	cout<<"after 'new(p) A(2);' p->a =  "<<p->a<<";\tpInt="<<(long long)p->pInt<<endl;
	//p->~A();//需要手動呼叫解構函式！！！


	cout<<"\n******************    test2"<<endl;
	char* s2=new char[sizeof(A)];
	A* p2 = (A*)s2;
	cout<<"before 'p2->A::A(3);' p2->a =  "<<p2->a<<";\tpInt="<<(long long)p2->pInt<<endl;
	p2->A::A(3);//placement new!!!!!!!!!!   的第二種寫法
	cout<<"after 'p2->A::A(3);' p2->a =  "<<p2->a<<";\tpInt="<<(long long)p2->pInt<<endl;
//	p2->~A();


	delete[] s;//編譯器不知道s中的內容是類A啊，不呼叫解構函式
	delete[] s2;

	//測試陣列
// 	cout<<"\n\\\\\\\\\\\\*****測試陣列"<<endl;
// 	A* aa=new A[10];
// 	delete[] aa;

	cout<<"\n******************   從main函式返回前的最後一句"<<endl;
}
 

[color=red][size=large]輸出如下：[/size][/color]
[img]http://dl.iteye.com/upload/attachment/0076/5596/9e5b559b-edb8-35ab-a3a0-8cb610fd102a.png[/img]