在阅读C++PrimerPlus时,我对placementnew有一些疑问。书中的示例代码是这样的:classJustTesting{private:stringwords;intnumber;public:JustTesting(conststring&s="JustTesting",intn=0){number=n;words=s;//somecodehere}~JustingTesting(){}};char*buffer=newchar[BUF];//getablockofmemoryJustTesting*pc1,*pc2;pc1=new(buffer)JustTesting