CBSE Class 12 Computer Science Class And Objects Worksheet Set B

1 Write the definition for a class called Rectangle that has floating point data members length and width. The class has the following member functions:

void setlength(float) to set the length data member

void setwidth(float) to set the width data member

float perimeter() to calculate and return the perimeter of the rectangle

float area() to calculate and return the area of the rectangle

void show() to display the length and width of the rectangle

int sameArea(Rectangle) that has one parameter of type Rectangle. sameArea returns 1 if the two Rectangles have the same area, and returns 0 if they don't.

1. Write the definitions for each of the above member functions.

2. Write main function to create two rectangle objects. Set the length and width of the first rectangle to 5 and 2.5. Set the length and width of the second rectangle to 5 and 18.9. Display each rectangle and its area and perimeter. 

3. Check whether the two Rectangles have the same area and print a message indicating the result. Set the length and width of the first rectangle to 15 and 6.3. Display each Rectangle and its area and perimeter again. Again, check whether the two Rectangles have the same area and print a message indicating the result.

1. Define a class STUDENT with the following specifications

Private members:

Grno                                                        long integer
Name                                                      20 characters
Marks in 5 subjects, each out of 100     an array of 5 float values
Total, percentage                                   float
Calculate()                                             Function to calculate total & percentage

Public functions

takedata() Function to read Grno, name and 5 marks of a student

displaydata() to invoke Calculate() function and to display all the details of the student

Write a Program to implement the above class for a student.

2. Define a class EMPLOYEE with the following specifications

Private data members
Empno               integer
Name                20 characters
Basicpay           float
HRA, DA, PF    float
Netpay             double

Public functions

Getdata() Function to read empno, name and basicpay of an Employee

Compute() Function to compute HRA (10% of basicpay), DA (50% of basicpay), PF (8% of basicpay) and netpay as basicpay + HRA + DA – PF and return the calculated Netpay.

Printdata() to invoke Compute() function and to display all the details of an employee

Write a Program to read details (empno, name and basicpay) for n employees and compute netpay for them and display all the details.

CLASSES AND OBJECTS 

Q1. What is class? What is its need? Classes
A class is a way to bind the data describing an entity and its associated functions together. In C++ , class makes a data type that is used to create objects of this type. Need for classes
Classes are needed to represent real-world entities that not only have data type properties (Characteristics) but also have associated operations (their behaviour)

Q2 . Differentiate between local and global class with help of example.
Answer : 1. Global Class
A class is said to be global it its declaration occurs outside the bodies of all functions in a program.
2. Local class
A class is said to be local if its occurs inside the function body
# include<iostream.h>
class x                            //x is a global class
{
members variable functions of class;
};
x ob1;                             //global object
int main ( )
{    
class num                         // num is local class
    {    
    public:
    int a=10;
    void num( )                    // constructor (same name of class)
    {
    cout<<num;
    };    
    x ob2;                            //local object of class x
    num n1;                         // n1is a class object
    n1.num( );
    }                                   // closing of main ()

Q3. What do you mean by nested class ?Explain.
Answer : Nested class
Declaration of one class in to another class is called is called nested of a class.
#include<iostream.h>
#include<conio.h>             // for clrscr()
class score
{
int a;            //private member variable
class batesman                   // nested class
{
int b;
public:
int c;
void total( )
{
cin>>b>>c;
int sum = b+c;
}
batesman( )
{
c=10;
}
};                                  // end of class batesman
batesman obj2;              // object of class batesman
void second( void)
{
cout<<score :: second()<<endl;
cout<<”A =” <<a
}
           score( )
           {
           a= 25;
           }
};        //end of class score;
void main()
{
           score ab;
           batesman bc;
           score :: batesman cd;
           ab.second();
           bc.total();
           cd.total();
}

Q4. What are the advantages and disadvantages of inline functions?
Answer : The main advantages of inline functions is that they save on the overheads of a function call as the function is not invoked, rather its code is replaced in the program.
The major disadvantage of inline functions is that with more function calls, more memory is wasted as for every function call, the same function code is inserted in the program. Repeated occurrences of same function code waste memory space.

Q5. What do you understand by member function?
Answer : Member function have full access privilege to both the public and private members of the class. These are defined within the class scope that is they are not visible outside the scope of class.
But not member functions are visible outside the class (ordinary functions)

Q6. What are static class members?
Answer : A class can have static data members as well as static member functions The static data members are the class variables that are common for all the objects of the class. Only one copy of static data members is maintained which is shared by all the objects of the class. They are visible only with in the class

Q7. Identify the errors in the following code fragment:
class ab
{
           int x;
           static int ctr;
Public:
    Void init(void)          {
    x=ctr=0;                   }
static void print(void)  {
    cout<<ctr<<x;         }            };
Answer : In the above code fragment, a static member function is trying to access a non static member that is ‘x’ which is the error
The correct code for static member function is
           static void print(void)
           {
           cout<<ctr;            }

Q8. What is the significance of access specifiers in a class?
Answer : A class provides three access specifiers namely private, public and protected
(a) A data member declared as private or protected remains hidden from outside world and it can only be accessed by the member functions of the class.
(b) A data member declared as public is made available to the outside world. That is, it can be accessed by any function, any expression in the program but only by using an object of the same class type.
These access labels enforce data hiding and abstraction also.

Q9 . Write the output of the following code
#include<iostream.h>
class counter                 {
private:
unsigned int count;
public:
counter()                     // constructor
    {
count=0;         }
void inc_count( )          // increment in count variable
{
count ++;             }
int get_count( )     {
return count;         }
                            };
void main()
{
counter c1,c2;
cout<< “ \n value for c1 is:” <<c1.get_count( );
cout<< “ \n value for c2 is:” <<c2.get_count( );
c1.inc_count();
c2.inc_count();
c2.inc_count();
cout<< “\t c1=” <<c1.get_count();
cout<< “\t c2=” <<c2.get_count();     }
Answer : The output will be
c1=0 c2=0 c1=1 c2=2

Chapter – 4 CONSTRUCTOR AND DESTRUCTORS

Q1. What is Constructor ?
Answer : Constructors:
A constructor is a special member function of a class that is automatically called, when an object is created of that class. A member function with the same name as its class is called constructor.

Q2. What is destructor ? What is its need ?
Answer : Destructor:
A destructor is also a member function whose name is the same as the class name but is preceded by tilde (‘~’)
A destructor takes no arguments and no return types can be specified for it. It is called automatically by the compiler when an object is destroyed. A destructor cleans up the storage ( memory area of the object) that is no longer accessible. Need for Destructors
Allocated resources (like constructor) must be de-allocated before the object is destroyed. It works as a de-allocating and releasing memory area and it perform our works as a clean up tasks. Therefore, a destructor is equally useful as a constructor is.
class stud
  {
    stud()                     //constructor
    { 
    cout << “ welcome”