Difference between Object var and Object* var = new Object()

Question

If I have a class named Object, what's the difference between creating an instance just like that:

Object var;

and:

Object* var = new Object();

?

Answer 1

Here you are creating var on the stack:

Object var;

So in the above, var is the actual object.

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Here you are creating var on the heap (also called dynamic allocation):

Object* var = new Object()

When creating an object on the heap you must call delete on it when you're done using it. Also var is actually a pointer which holds the memory address of an object of type Object. At the memory address exists the actual object.

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For more information: See my answer here on what and where are the stack and heap.

Answer 2

This:

Object var();

Is a function declaration. It declares a function that takes no arguments and returns an Object. What you meant was:

Object var;

which, as others noted, creates a variable with automatic storage duration (a.k.a, on the stack).