最近，有个童鞋问我，他对下面这种 new的奇怪写法不明白，很怪异，不像平时的用法，

其实这个是new的一种用法而已，只是他接触的少，所以迷糊了，看看下面的代码，大家就知道为什么可以这么写了！

#include <iostream>
using namespace std;void* operator new(size_t size)
{cout << "全局new重载		" << size << endl;return malloc(size);
}class  A
{double d;
public:A(double d1 ): d(d1){   cout <<d<< "构造函数" << endl;}~A( )  {cout << d << "析构函数" << endl;}void * operator  new(size_t  size ){cout << "类new重载方式一" << size << endl;;return  malloc(size);}//----------------------placement new操作符-------------------------------- void* operator  new(size_t  size , int param1){cout << "类new重载方式二" << size <<"    "<< param1 << endl;;return  malloc(size);}void* operator  new(size_t  size, int param1,string  param2){cout << "类new重载方式三" << size << "    " << param1 << "    " << param2 << endl;;return  malloc(size);}
};int  main()
{short* pS = new short ; A* pA = new A(0.11);delete pA;A* pA2 = new  (12)  A(0.22)  ; delete pA2;A* pA3 = new  (12,"hello")  A(0.33);delete pA3;return 0;}

运行效果图，方式二  与   方式三  就是上述的怪异写法