C++ MCQ Questions - Classes & Objects

11. What is the output of this program?

         
Note:Includes all required header files
using namespace std;
  
class Empty {};
  
int main()
{
  cout << sizeof(Empty);
  return 0;
}

A. A non-zero value.
B. 0
C. Compiler Error
D. Runtime Error

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12. What is the output of this program?

         
Note:Includes all required header files
using namespace std;
 
class Empty { };
 
class Derived: Empty { int a; };
 
int main()
{
    cout << sizeof(Derived);
    return 0;
}

A. 1
B. 2
C. 4
D. Error

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13. What is the output of this program?

       
Note:Includes all required header files 
class Test 
{
  int x; 
};

int main()
{
  Test t;
  cout << t.x;
  return 0;
}

A. 0
B. Garbage value
C. Runtime error
D. Complier error

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14. Assume that an integer and a pointer each takes 4 bytes. Also, assume that there is no alignment in objects. Predict the output following program.

         
Note:Includes all required header files
using namespace std;
 
class Test
{
    static int x;
    int *ptr;
    int y;
};
 
int main()
{
    Test t;
    cout << sizeof(t) << " ";
    cout << sizeof(Test *);
}

A. 12 12
B. 12 4
C. 8 4
D. 8 8

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15. Which of the following is true about the following program

#include <iostream>
using namespace std;
class LFC 
{ 
public: 
    int i; 
    void get(); 
}; 
void LFC::get() 
{ 
    std::cout << "Enter the value of i: "; 
    std::cin >> i; 
} 
LFC t;  
int main() 
{ 
    LFC t;  
    t.get(); 
    std::cout << "value of i in local t: "<<t.i<<'\n'; 
    ::t.get();  
    std::cout << "value of i in global t: "<<::t.i<<'\n'; 
    return 0; 
}

A. Compiles and runs fine
B. Compiler Error in Line "::t.get();"
C. Compiler Error: Cannot have two objects with same class name
D. Runtime error

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16. What will be the output of this program?

         
Note:Includes all required header files
using namespace std;
 
class sample
{
    int x;
}
 
int main()
{
    sample obj;
    obj.x=100;
    cout<<"x="<< obj.x; 
}

A. 10
B. 100
C. Error
D. None of the above

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17. What will be the output of this program?

        
Note:Includes all required header files
using namespace std;
//Empty class
class test
{
};
 
int main()
{
   test testObj;
   cout<<"size ="<< sizeof(testObj);
   return 0;
}

A. Error
B. size =Garbage
C. size =1
D. Compile but no output

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18. What will be the output of the following program?

#include <iostream>
using namespace std;
class LFC 
{ 
    public: 
      int x; 
}; 
int main() 
{ 
    LFC *p = new LFC(); 

    (*p).x = 5; 
    cout<< (*p).x << " " << p->x << " " ; 

    p->x = 10; 
    cout<< (*p).x << " " << p->x ; 

    return 0; 
} 
 

A. 5 5 10 10
B. Garbage garbage 10 10
C. 5 5 Garbage garbage
D. Garbage garbage Garbage garbage

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19. Which of the following statements is correct when a class is inherited publicly?

A. Public members of the base class become protected members of derived class.
B. Public members of the base class become private members of derived class.
C. Private members of the base class become protected members of derived class.
D. Public members of the base class become public members of derived class.

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20. What does the cerr represent?

A. Standard error stream
B. Standard logging stream
C. Input stream
D. Output stream

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