Constructor, Copy Constructor, Destructor - PowerPoint Presentation

Slide1

Constructor, Copy Constructor, Destructor

Prepared for

C

I

B

126

Pemrograman

Berorientasi

Objek

By

Indriani

Noor

Hapsari

, ST, MT

Source:

Walter Savitch, Problem Solving using C

++.

https://

www3.ntu.edu.sg/home/ehchua/programming/cpp/cp3_OOP.html#zz-2.20

Slide2

Constructor

Description

A

constructor is a special member function in a class whose purpose is usually to initialize the members of an object.A constructor is easy to recognize because:It has the same name as the class.It has no return type.

2Slide3

Constructor

Declaration

A constructor must have the same name as its class.

Constructor cannot return values, even void.Normally, constructors are declared as public.3Slide4

A copy constructor constructs a new object by copying an existing object of the same type. In other words, a copy constructor takes an argument, which is an object of the same class.

If you do not define a copy constructor, the compiler provides a default which copies all the data members of the given object

.

The copy constructor is particularly important. When an object is passed into a function by value, the copy constructor will be used to make a clone copy of the argument.Copy ConstructorSlide5

Example

Copy ConstructorSlide6

Pass-by-value for object means calling the copy constructor. To avoid the overhead of creating a clone copy, it is usually better to

pass-by-reference-to-

const

, which will not have side effect on modifying the caller's object.Copy ConstructorSlide7

A destructor, similar to constructor, is a special function that has the same name as the

classname

, with a prefix ~, e.g., ~Circle(). Destructor is called implicitly when an object is destroyed.

If you do not define a destructor, the compiler provides a default, which does nothing.If your class contains data member which is dynamically allocated (via new or new[] operator), you need to free the storage via delete or delete[]DestructorSlide8

Example

Destructor

delete [] a;Slide9

End of slides.