Question about inheritance

Suppose I have a base class with a virtual function that simply returns 140.

Now suppose I have a derived class, that extends the base class. Here, I make the virtual function return 230.

Suppose this fucntion is named ret_int().

Now, if I have a function that accepts a pointer to the Base class

Code:

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function(Base * b)

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that calls the ret_int() function.

if I pass in a pointer to derived, will it return 140, or 230?

Write a program to test and report your results.

very complicated position where I can't do that.. no compiler (government machine)

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Originally Posted by dayalsoap

very complicated position where I can't do that.. no compiler (government machine)

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Wait until you have access to a computer with which you can program then.

By the way, what do you think the answer is, and why?

I mean, if you know about inheritance, you can answer the question. if you don't then what's the point of answering with "test it!" Clearly, there's a reason I can't test it right now and need to know sooner than later.

My guess is, even though it accepts a ptr to the base class, since we've instantiated an instance of the sub-class, it will use the sub-classes functionality.

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Originally Posted by dayalsoap

I mean, if you know about inheritance, you can answer the question.

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Yes, inheritance is involved, but here we're talking about polymorphism :)

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Originally Posted by dayalsoap

if you don't then what's the point of answering with "test it!" Clearly, there's a reason I can't test it right now and need to know sooner than later.

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There is no point knowing if you cannot use the knowledge, and one powerful way to acquire the knowledge is to see the behaviour happen, first hand.

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Originally Posted by dayalsoap

My guess is, even though it accepts a ptr to the base class, since we've instantiated an instance of the sub-class, it will use the sub-classes functionality.

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Good guess :)
In fact, I would change "even though" to "because": if the parameter was changed to be a Base instead of a Base*, there would be slicing, so the base class' implementation would be invoked.

Quote:

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Originally Posted by dayalsoap

very complicated position where I can't do that.. no compiler (government machine)

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Hmm.....Comeau Compiler.

Egad , it's quite typical of laymen programmers to be pedantic. Anyways, thanks for your answer, finally, pedantic layman.

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Originally Posted by laserlight

Yes, inheritance is involved, but here we're talking about polymorphism :)


There is no point knowing if you cannot use the knowledge, and one powerful way to acquire the knowledge is to see the behaviour happen, first hand.


Good guess :)
In fact, I would change "even though" to "because": if the parameter was changed to be a Base instead of a Base*, there would be slicing, so the base class' implementation would be invoked.

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That would have been perfect! Thank you!

it's interesting that you insult those from whom you seek help, and refuse to even try to find your own answer. a simple google search would have provided the answer you seek.

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Originally Posted by AndrewHunter

Hmm.....Comeau Compiler.

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Oh, that compiles the code, but you won't be able to run it afterwards.

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Originally Posted by dayalsoap

Egad , it's quite typical of laymen programmers to be pedantic. Anyways, thanks for your answer, finally, pedantic layman.

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You're welcome. Yeah, my degree is in computer science, not theology, and software development is my current profession, hence I am a layman. I do not know any ordained programmers though, so I cannot say if they are actually more pedantic than me :)