Object Oriented Programming
Techniques
Constructor
• Special method that is invoked automatically at the time of object creation
• Initialize the data members for an object of a class automatically, when an
object of the same class is created
• Same name as the class or structure
• Automatically called by the compiler
• Invoked at the time of object creation
• Constructor do not return value
• Do not have a return type
• Constructors may not be static.
Syntax
<class-name>(list-of-parameters)
{
//constructor definition
}
Example code
class Table
{
Public: Table()
{}
};
Example Code Constructor Within The Class
Output
Example Code Constructor Outside The Class
Scope Resolution Operator (::)
Example Code Constructor Outside The Class
Output
Types of Constructor
Default Constructor
• No arguments are passed
• The compiler will give an implicit default constructor if the
programmer does not explicitly provide one
• Each time an object is created, a constructor is invoked
Example Default Constructor
Output
Example Default Constructor
Output
Example Explicit Default Constructor
Output
Parameterized Constructors
• Pass arguments to constructors
• Arguments help initialize an object when it is created
Example Parameterized Constructors
Output
Example Parameterized Constructors
Output
Example Parameterized Constructors
Output
Copy Constructor
• Creates an object by initializing it with a previously created object of
the same class
Example Copy Constructor
Example Copy Constructor
Output
Example Copy Constructor
Example Copy Constructor
• Notice that the parameter of this
constructor
• It has the address of an object of
the Wall class.
Dry Run for Output
Output
Destructor
• Special member function as a constructor
• Destructor destroys the class objects created by the constructor
• Same name as their class name preceded by a tilde (~) symbol
• It is not possible to define more than one destructor
• Destructor can-not be overloaded.
• Neither requires any argument nor returns any value.
• Automatically called when the object goes out of scope
• Release memory space occupied by the objects created by the
constructor
Syntax
~ <class-name>()
{
}
Example
Output
Example
Output
Task
• Write a C++ program to create a class named Table. The class has
constructor and destructor along with another member function
named Multiply. Multiply function will print the table up till 10 for the
value through main taken from parameterized constructor.