条款52:写了placement new 也要写placement delete(write placement delete if you write placement new)

NOTE:

        1.当你写一个placement operator new .请确定也要写出了对应的placement operator delete。如果没有这样做，你的程序可能发生隐晦而时断时续的内存泄漏。        1.当你写一个placement operator new .