The * in C++ Initialisations

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The Definitive C++ Book Guide and List

I'm new to C++ and have been playing around witha few examples, I was just wondering what the * meant when initialising a class.

Normally in AS3 I would do this:

MyClass myClass = new MyClass

But I have seen this in c++

 MyClass *myClass = new MyClass

What is the star for, I;ve seen it used sometimes and not others.

Thanks!

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The asterisk in C++ means many things depending on its place in the program. In this specific instance, it modifies the meaning of myClass to be a pointer to an instance of MyClass , rather than an instance of MyClass .

The difference between the two is that the lifetime of an instance ends when it goes out of scope, while an instance that you allocate and reference through a pointer remains valid even after a pointer goes out of scope.

It is valid to have a declaration like this:

MyClass myClass; // no "new"

In this case, it is not necessary to use new , but the instance's life time is tied to the scope of the variable myClass .

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An asterisk stand for a pointer . A pointer is a memory adress. When you write MyClass *myClass , you create a pointer to the beginning of the bits range where your new MyClass is created.

Creating an object with new , you become responsible of it life cycle. YOU will need to delete it when you dont need them anymore, whereas creating MyClass myClass; will be destroy when exiting the scope where you create it. You still can access myClass memory adress even when written this way, using & operator.

If you need more explaination, try to get one of those books.

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