What is difference between instantiating an object using new vs. without
In C++,
Aside from dynamic memory allocation, is there a functional difference between the following two lines of code:
Time t (12, 0, 0); //t is a Time object
Time* t = new Time(12, 0, 0);//t is a pointer to a dynamically allocated Time object
I am assuming of course that a Time(int, int, int) ctor has been defined. I also realize that in the second case t will need to be deleted as it was allocated on the heap. Is there any other difference?
Answer
The line:
Time t (12, 0, 0);
... allocates a variable of type Time in local scope, generally on the stack, which will be destroyed when its scope ends.
By contrast:
Time* t = new Time(12, 0, 0);
... allocates a block of memory by calling either ::operator new() or Time::operator new(), and subsequently calls Time::Time() with this set to an address within that memory block (and also returned as the result of new), which is then stored in t. As you know, this is generally done on the heap (by default) and requires that you delete it later in the program, while the pointer in t is generally stored on the stack.