Explanation about constructor and destructor

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Hi All

Can some explain what are the affects of accessibility of constructor and destructor on scope and the visibility of their class.

Regards

Posted 20-Jun-13 6:28am

vishal deb

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Richard MacCutchan · Answer 1 · 2013-06-20T07:06:00

Solution 1

See http://msdn.microsoft.com/en-us/library/4a1hcx0y.aspx[^] for details on classes.

Posted 20-Jun-13 7:06am

Richard MacCutchan

Comments

vishal deb 20-Jun-13 13:40pm

@Richard MacCutchan Thank you for your link
But I need a glass of water and you thrown me in Swimming Pool.

Please give me some easy explanation as I am in learning phase not an expert like you.

JackDingler 20-Jun-13 13:48pm

Your question is so broad, that you need long winded explanation to answer it.

Sergey Alexandrovich Kryukov 20-Jun-13 18:03pm

Let me explain you what happened in fact.

You jumped in a pool of water and started to sink. It brought you to the question you are starting to shout to the people who you want to save your: "Hey, help me! Tell me how a water molecule works". :-)

Not really helpful. You should really step back and start learning programming on some regular basis, starting from the basics of OOP, if not from the very beginning. Casual questions on forums cannot help you.

—SA

Richard MacCutchan 21-Jun-13 2:35am

You need to walk before you can run. Asking a question such as this suggests that you need to go back to the basics of C++ and study it from the beginning. Nothing can change that.

vishal deb 20-Jun-13 13:56pm

@JackDingler
I have a small theory can you verify my concept -
Accessibility of a class's constructors and destructor only affects the creation or destruction of object of that class. You will need at least one of the publicly accessable constructors or destructor for creating or destructing object of a class.

JackDingler 20-Jun-13 14:38pm

That explanation helps me understand what you're asking.

To create or a destroy a class from code that isn't a friend or member of a class, you need a public constructor and destructor.

You can create and destroy a class with private or protected constructors and destructor from a static method in the class. In the case of a protected constructor / destructor, a freiend of the class or a derived class can instantiate it.

Sergey Alexandrovich Kryukov 20-Jun-13 18:03pm

My 5. As to the question about the Swimming Pool OP asked you, I think I answered it in my comment above. :-)
—SA

H.Brydon · Answer 2 · 2013-06-20T17:49:00

First, let me say that I am writing this from memory, so there may be errors; check my statements.

If a class has public ctor and dtor, then it can be created anywhere by any code (assuming there are no issues with pure virtual methods etc.).

If a class has a protected constructor, then only a derived class can be instantiated.

If a class has a protected/private destructor, it can be created/deleted as a static object, or on the stack but not on the heap. Or using a factory method.

If a class has a private constructor (and no friends) it can be created using a factory method but not static, stack or heap.

This looks like homework; validate my statements above with some code. I might be wrong...