CSimpleArray ?

[ZBUILDER]

Excuse me. Today,I study the WTL Library's CSimpleArray class source code,I find the following code:

template<class T>
class CSimpleArray
{
      T* m_aT;
      ...

	class Wrapper
	{
	public:
		Wrapper(T& _t) : t(_t)
		{
		}
		template 
		void *operator new(size_t, _Ty* p)
		{
			return p;
		}
		T t;
	};
	void SetAtIndex(int nIndex, T& t)
	{

		new(&m_aT[nIndex]) Wrapper(t);
	}
   ...
}

I can not understand the syntax about "new(&m_aT[nIndex]) Wrapper(t)":confused:,anyone can explain it? thanks first. SIMPLE IS BEAUTY

[Renjith Ramachandran]

ZBUILDER wrote: I can not understand the syntax about ZBUILDER wrote: new(&m_aT[nIndex]) Wrapper(t); returns the pointer and that new allocates using that pointer * * * Code the dreams * * *

[ZBUILDER]

Then What about Wapper(t)? And How does it modify the Adderss of &m_aT[nIndex]? SIMPLE IS BEAUTY

[Jorgen Sigvardsson]

It's called placement new. You're executing the Wrapper-constructor on an already allocated memory block. -- Only in a world this shitty could you even try to say these were innocent people and keep a straight face.

[Jorgen Sigvardsson]

ZBUILDER wrote: new(&m_aT[nIndex]) Wrapper(t) It's called placement new. It executed the constructor Wrapper(t) on a preallocated memory block &m_aT[nIndex]. So basically, you're telling new not to allocate new memory for the object but use existing memory. -- Only in a world this shitty could you even try to say these were innocent people and keep a straight face.