C++ Institute Exam CPA Topic 7 Question 84 Discussion

Actual exam question for C++ Institute's CPA exam

Question #: 84
Topic #: 7

[All CPA Questions]

What happens when you attempt to compile and run the following code?

#include

using namespace std;

class A {

public :

void print() {

cout << "A ";

}

};

class B {

public :

void print() {

cout << "B ";

}

};

int main() {

B sc[2];

B *bc = (B*)sc;

for (int i=0; i<2;i++)

(bc++)->print();

return 0;

}

AIt prints: A A

BIt prints: B B

CIt prints: A B

DIt prints: B A

Show Suggested Answer

Suggested Answer: B

by Alishia at Apr 10, 2024, 03:07 AM

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Freida

6 months ago

I think the answer is C as well. The increment in the pointer changes the print order.

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Glennis

6 months ago

I'm not sure, but I think it might be D because of how the pointers are being used.

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Viva

6 months ago

I agree with Tatum, the code makes use of pointer arithmetic to print A B.

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Tatum

6 months ago

I think the answer is C because it alternates between A and B.

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Crista

6 months ago

I think because we are incrementing the pointer to class B and then calling the print function

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Shenika

6 months ago

But why do you think it prints: B B?

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Pamela

6 months ago

I disagree, I believe it prints: B B

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Crista

7 months ago

I feel like it may print: A B too

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Shenika

7 months ago

I think it prints: A B

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You know, I'm starting to wonder if the answer is actually D) B A. Think about it - we're casting the sc array to a B* pointer, but the underlying objects are actually A objects. So when we call print() on the B* pointer, it should invoke the print() function of the A class, right? Hmm, I'm not totally sure, but that's my best guess.

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Gladys

8 months ago

Haha, I bet the exam writers are just trying to trip us up with this one. They're probably hoping we'll overthink it and second-guess ourselves. I'm just going to go with my gut and say it prints B B. What could be simpler than that?

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Shawnna

8 months ago

Hold on, I'm not so sure about that. If the objects are actually A objects, shouldn't it be printing A A? Or maybe it's going to print A B since we're accessing the objects through a B* pointer? This is really confusing, I need to think this through more carefully.

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Katie

8 months ago

I think the key here is the casting of the sc array to a B* pointer. Since we're calling print() on the B* pointer, it's going to invoke the print() function of the B class, even though the underlying objects are actually A objects. So my guess is that it's going to print B B.

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Vicky

8 months ago

Okay, let's take a closer look at this. We've got two classes, A and B, both with a print() function that prints out their respective letters. Then in the main function, we create an array of B objects and cast it to a B* pointer. Finally, we loop through and call the print() function on each element. Hmm, this is tricky.

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Belen

7 months ago

I think it will print 'A B' because we are casting the array of B objects to a B* pointer and calling the print() function on each element.

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Luther

7 months ago

C) It prints: A B

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Wayne

8 months ago

Whoa, this question looks like a real mindbender! I'm not even sure what's going to happen when I run this code. Is it going to print A A, B B, A B, or B A? My brain is already starting to hurt just thinking about it.

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C++ Institute Exam CPA Topic 7 Question 84 Discussion

Contribute your Thoughts:

Freida

Glennis

Viva

Tatum

Crista

Shenika

Pamela

Crista

Shenika

Luann

Gladys

Shawnna

Katie

Vicky

Belen

Luther

Wayne