c++ dynamic allocation with new

Question

What's the difference between these two allocations?

CPolygon trgl;
CPolygon * ppoly2 = &trgl;

and

CPolygon * ppoly2 = new CPolygon();

You should delete the 2nd one, but mustn't delete the first one. — doctorlove, Jan 06 '14 at 12:22
@Adriano True. Even better, you could accompany such comments with a link to the [list of good C++ books](http://stackoverflow.com/q/388242/1782465) here on SO. — Angew is no longer proud of SO, Jan 06 '14 at 12:32
@Angew I added that post to my favorites, next time I'll use it! — Adriano Repetti, Jan 06 '14 at 13:02

score 2 · Accepted Answer · answered Jan 06 '14 at 12:21

new creates a dynamic object on the heap, while the first syntax create the object either in the global memory section, or on the stack.

As a consequence, if the object is allocated on the stack, it will be automatically deleted if the object goes out of scope. If the object is global, it will stay for the liftime of the process.

Object allocated with new would have to be deleted with delete.

c++ dynamic allocation with new

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