new operator and class-type instance members

[Andrew Shap]

Hi,

I have a simple question about using the new operator on classes with instance members of other class types. If I have a class foo with the following definition:

class Foo {
	public:
		Foo1 foo1;
		Foo2 foo2;
	};

and I write the following in my main():

static Foo* foo = new Foo;

...does that allocate memory for the instance members foo1 and foo2 as well? I know that instantiating a Foo type calls the constructors for its instance members (Foo1 and Foo2), but is writing the above allocation the same as:

Foo1* _foo1 = new Foo1;
Foo2* _foo2 = new Foo2;

(foo->foo1) = (*_foo1);
(foo->foo2) = (*_foo2);

If not, how do I allocate memory for the instance members? Likewise, does explicitly calling the destructor for Foo, also deallocate memory of its instance members foo1 and foo2?

Thanks,

Andrew

[jsmith]

Your first example is right; your second is a memory leak.

And yes, Foo's destructor will implicitly run the destructor for all of the data members of Foo.

There is very rarely ever a need for you to call a destructor explicitly.