dynamically allocating a c++ object without using the new operator

Question

(C++/Win32)

consider the following call:

Object obj = new Object(a,b);

other than allocating the virtual memory needed for an instance of an Object , what else is going on under the hood up there? does the compiler places an explicit call to the constructor of Object ?

is there any way to initialize a c++ object dynamically without the use of the keyword new ?

Answer 1

If you want to initialize an object in some given memory zone, consider the placement new (see this )

BTW, the ordinary Object* n = new Object(123) expression is nearly equivalent to (see operator ::new )

 void* p = malloc(sizeof(Object));
 if (!p) throw std::bad_alloc; 
 Object* n = new (p) Object(123); // placement new at p, 
                                  // so invokes the constructor

^{But the implementation could use some non- malloc compatible allocator, so don't mix new and free !}

Answer 2

You can always use malloc instead of new, but don't forget to always couple it with free and not delete .

See also : What is the difference between new/delete and malloc/free?