C++ FAQs, Second Edition

Chapter 12. New and Delete

FAQ 12.01 Does new do more than allocate memory?

Yes, it also initializes the new object.

Assuming Fred is a known type, the expression new Fred() is a two-step operation. The first step is to allocate sizeof(Fred) bytes of memory using a memory allocator primitive called operator new(size_t nbytes) (size_t is a typedef for an unsigned integral type such as unsigned int). This memory allocation primitive is conceptually similar to but not interchangeable with malloc(size_t nbytes). The second step is to call the appropriate constructor of the class (Fred::Fred() in this case).

Similarly, delete p is a two-step operation: it first calls the destructor on the object *p, then it releases the memory pointed to by p using ...