Advanced-C++/C2/Constructor-And-Destructor/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on Constructors and Destructors in C++.
00:07	In this tutorial, we will learn:
00:09	* Constructors
00:10	* Types of constructors
00:12	* Destructors.
00:13	We will do this with the help of some examples.
00:17	To record this tutorial, I am using:
00:20	* Ubuntu Operating System version 11.10,
00:23	* g++ Compiler version 4.6.1
00:28	Let us start with an introduction to Constructor.
00:31	A constructor is a member function.
00:33	It has the same name as the class name.
00:37	Constructors cannot return values.
00:40	It is automatically called when an object is created.
00:44	Types of Constructors :
00:46	* Parameterized Constructors
00:49	* Copy Constructors and
00:50	* Default Constructors.
00:53	Let us move on to Destructors.
00:56	Destructors are used to deallocate memory.
00:59	They are called when an object is destroyed.
01:02	A destructor takes no arguments and has no return types.
01:07	Let us see an example on Constructors and Destructors.
01:11	I have already typed the code on the editor, I will open it.
01:15	Note that our filename is cons hyphen dest dot cpp.
01:20	In this program, we will perform the addition of two numbers using constructor.
01:25	Let me explain the code now.
01:27	This is our header file as iostream.
01:30	Here we have used std namespace.
01:33	Then we have class Addition. a and b are the integer variables.
01:38	These are the private members of class Addition.
01:42	Here we have the Public specifier.
01:44	Then we have the construtor Addition.
01:47	The constructor has the same name as the class name.
01:52	We have passed two arguements here.
01:54	Now we have defined a Destructor.
01:57	For this we use a tilde sign followed by the destructors name.
02:02	This is a public function add.
02:05	It returns sum of a and b.
02:08	Here, we access the constructor using the scope resolution operator.
02:12	'a' and 'b' are private members.
02:15	To access the private members, we use x and y.
02:19	Then we access the destructor.
02:21	In this, we print "Memory Deallocation".
02:25	This is our main function.
02:28	Here, we create an object obj of class Addition.
02:32	Then we pass two arguments as 3 and 4.
02:36	3 will be stored in 'x' and 4 will be stored in 'y'.
02:40	This means 'a's value is 3 and 'b's value is 4.
02:45	The constructor that has arguments is called parameterized constructor.
02:50	Hence this one is the prameterized constructor.
02:53	Here, we call the function add using the object obj.
02:58	And we print the sum.
03:00	This is our return statement.
03:02	Now let us execute the program.
03:05	Open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard.
03:12	To compile, type: g++ space cons hyphen dest dot cpp space hyphen o space cons
03:21	Press Enter.
03:23	Type: dot slash cons
03:25	Press Enter.
03:27	The output is displayed as:
03:29	Sum is 7 and Memory Deallocation.
03:33	Now let us see an example on Default constructors.
03:37	Come back to our program.
03:39	I have already typed the code.
03:41	Note that our file name is default dot cpp.
03:45	If a constructor is not declared in the class
03:48	then the compiler assumes a default constructor for the class.
03:53	Let me explain the code.
03:55	This is our header file as iostream.
03:58	Here we have used std namespace.
04:02	Then we have class Subtraction.
04:04	Then we have a and b declared as public.
04:08	Here, we have sub function.
04:10	We have passed two arguments int a and int b.
04:15	This returns the subtraction of two numbers 'a' and 'b.'
04:19	This is the defalut constructor.
04:22	Here, we access the default constructor using the scope resolution operator.
04:27	This is our main function.
04:29	In this, we have defined a variable 'x.'
04:34	Here we create an object 's' of class subtraction.
04:39	Then we call the function sub using the object s.
04:42	And pass two arguments as 8 and 4.
04:47	The result is stored in variable x.
04:51	And here we print the difference.
04:54	This is our 'return' statement .
04:56	Now, let us execute the program.
04:58	Come back to our terminal.
05:01	Let us compile, type: g++ space default dot cpp space hyphen o space def
05:09	Press Enter.
05:10	Type: dot slash def
05:12	Press Enter.
05:14	The output is returned as:
05:16	Difference is 4.
05:18	Come back to our program.
05:20	Here you can see that we have passed the arguments within the function.
05:25	And in our previous example, we have passed the arguments within the Object.
05:30	And here we have passed the arguments using the Object.
05:34	Now, let us go back to our slides.
05:38	Let us summarize. In this tutorial we learned:
05:41	* Constructor. eg. Addition
05:43	* Parameterized Constructor. eg. Addition obj (3, 4);
05:48	* Destructor. eg. ~Addition
05:52	* Default Constructor. eg. Subtraction
05:55	As an assignment, create a class named Division.
05:59	Create a constructor for the class.
06:01	And create a function divide which divides two given numbers.
06:06	Watch the video available at the link shown below.
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06:47	This is Ashwini Patil from IIT Bombay, signing off. Thank You for joining.

Contributors and Content Editors

Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14