Question

KNOWING C++ CLASSES

The below program either violates or misses 5 areas of object-oriented programming in C++ including:

Data encapsulation.
Accessibility.
Separate class declaration and definition.
The class is missing some important component even though they're not significant. In general we should explicitly specify class components instead of relying on compiler provided components.
getters must not modify member data.
Syntax error in main function.

Identify the problems (6 of them, 3 pts each), explain the problems in short sentences and provide a code fix.

#include <iostream.h>

class FinalExam {

private:

FinalExam ( int m_score) : score (m_score) { }

public:

int score;

int get_score ( ) { return score ; }

void TakeExam ( ) {

cout << "Start taking exam ....\n";

}

} ;

int main ( ) {

FinalExam final_exam;

final_exam.TakeExam ( );

return 0;

}

Answer 1

Thanks for the question, here are the answers to all the parts.

=======================================================

Problem 1: constructor() should be a public but its declared as private
Problem 2: int score; is a member variable and should be marked as private but here its marked as public

Problem 3: when creating an object FinalExam final_exam we are not passing any intialization value, so it will not compile
Problem 4: the method are all inline functions that is they are implemented inside the class body, they should be defined outside the class
Problem 5: The class should also have a default constructor which is missing in the class
Problem 6: The class is also missing a copy constructor instead of relying on the compiler to provide a default one
Problem 7: The class should have a setter function for the member variable score

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Here is the corrected code.

#include<iostream>
using namespace std;

class FinalExam{
private:
int score;
public:
FinalExam();
FinalExam(int);
FinalExam(const FinalExam&);
int get_score() const;
void set_score(int);
void TakeExam();
  
};

FinalExam::FinalExam():score(0){}
FinalExam::FinalExam(int m_score):score(m_score){ }

FinalExam::FinalExam(const FinalExam& exam):
score(exam.score){ }
int FinalExam::get_score() const{return score;}
void FinalExam::set_score(int aScore){
score=aScore;
}void FinalExam::TakeExam(){
cout<<"Take Exam..\n";
}

int main(){
FinalExam final_exam;
final_exam.TakeExam();
}

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