placement new and delete

Question

What is the right method to delete all the memory allocated here?

  const char* charString = "Hello, World";
  void *mem = ::operator new(sizeof(Buffer) + strlen(charString) + 1);
  Buffer* buf = new(mem) Buffer(strlen(charString));

  delete (char*)buf;

OR

  const char* charString = "Hello, World";
  void *mem = ::operator new(sizeof(Buffer) + strlen(charString) + 1);
  Buffer* buf = new(mem) Buffer(strlen(charString));

  delete buf;

or are they both same?

Answer 1

The correct method is:

buf->~Buffer();
::operator delete(mem);

You can only delete with the delete operator what you received from the new operator. If you directly call the operator new function, you must also directly call the operator delete function, and must manually call the destructor as well.