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

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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 Constructors.
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 destructor's 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 filename 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 Then 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 * Constructors. eg. Addition
05:43 * Parameterized Constructor. eg. Addition obj (3, 4);
05:48 * Destructors. 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