9.1

Identify the error in the following program.

#include <iostream>;
using namespace std;
class  Info
{
      char* name;
      int Number;
public:
      void getInfo() 
      {
           cout << "Info::getInfo";
           getName();
      }
       
       void getName() 
       {
            cout << "Info::getName";
       }
};
 
class Name: public Info 
{
          char *name;
public:
         void getName()
       {
                 cout << "Name::getName";
       }
};
void main()
{
     Info *P;
     Name n;
     P = n;
     p->getInfo();   
}
/*
Answer

Here P=n will replace with P=&n in the main() function. Because P is a pointer.

9.2

Identify the error in the following program.

#include <iostream>;
using namespace std;
class  Person
{
      int age;
public:
      Person() 
      {
      }
       
       Person(int age) 
       {
            this.age = age;
       }
       Person& operator < (Person &p)
       {
            return age < p.age? p: *this;
       }
       int getAge()
       {
           return age;   
       }
};
 
void main()
{
     Person P1 (15);
     Person P2 (11);
     Person P3;
     //if P1 is less than P2
      P3 =  P1 < P2; P1.lessthan(P2)
      cout << P3.getAge();  
}
/*
Answer

The function

person (int age)
{
    this.age = age;
}

 

should write like as…

person (int age)
{
    this > age = age;
}
9.3

Identify the error in the following program.

#include <iostream>;
using namespace std;
class  Human
{
public:
      Human() 
      {
      }
       
       virtual -Human() 
       {
            cout << "Human::-Human";
       }
};
class Student: public Human
{
public:
      Student()
      {
      }
      -Student()
     {
           cout << "Student::-Student()";
     }  
};
 
void main()
{
     Human *H = new Student();
     delete H;  
}
Answer

Here we cannot write Human *H = new student(); in the main() function because base class’s member includes in derived class’s object so we should write this as follow
student *H = new Student();

9.4

Correct the errors in the following program.

class  Human
{
private:
      int m;
public:
      void getdata() 
      {
             cout << " Enter number:";
             cin >> m;
      }
};
main()
{
     test T;
     T->getdata();
     T->display();
     
     test *p;
     p = new test;
     p.getdata();
     (*p).display();   
}
Answer

Here T->getdata replace with T.getdata and T->display replace with T.display in the main() function. Because in this program T is object to pointer.

9.5

Debug and run the following program. What will be the output?

#include<iostream>
using namespace std;
class  A
{
protected:
      int a,b;
public:
      A(int x = 0, int y)
      {
             a = x;
             b = y;
      }
      virtual void print ();
};
class B: public A
{
     private:
        float p,q;
     public:
        B(intm, int n, float u, float v)
         {
              p = u;
              q = v;
         }
         B() {p = p = 0;}
         void input(float u, float v);
         virtual void print(loat);
};
void A::print(void)
{
     cout << A values: << a <<""<< b << "\n";
}
void B:print(float)
{
     cout << B values: << u <<""<< v << "\n";
}
void B::input(float x, float y)
{
     p = x;
     q = y;
}
main()
{
     A a1(10,20), *ptr;
     B b1;
     b1.input(7.5,3.142);
 
     ptr = &a1;
     ptr->print();
   
     ptr = &b1;
     ptr->print();   
}
Answer

The virtual keyword must write in base class and prototype base class and derived base class of print function should same.

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