Difference between revisions of "Advanced-C++/C2/Constructor-And-Destructor/English-timed"

| Welcome to the spoken tutorial on Constructors and Destructors in C++.

| In this tutorial we will learn,

| '''Constructors'''

 

| '''Types of constructors'''

| '''Destructors.'''

 

| We will do this with the help of some examples.

| To record this tutorial, I am using

| '''Ubuntu Operating System''' version 11.10,

| '''g++''' '''Compiler''' version 4.6.1.

| Let us start with an introduction to '''Constructors. '''

| A '''constructor''' is a member function.

| It is automatically called when an object is created.

| '''Parameterized Constructors.'''

| '''Copy Constructors.'''

| And '''Default Constructors.'''

| Let us see an example on '''Constructors and Destructors''',

| I have already typed the code on the editor, I will open it.

| Note that our filename is '''cons hyphen dest dot cpp'''

| In this program we will perform the addition of two numbers using constructor.

| This is our '''header file as iostream'''

| Here we have used '''std''' namespace.

| Then we have class '''Addition'''. '''a''' and '''b''' are the integer variables.

|These are the private members of class '''Addition.'''

| Then we have the construtor '''Addition'''

| The '''constructor''' has the same name as the class name.

| We have passed two arguements here.

| Now we have defined a Destructor.

| For this we use a '''tilde''' sign followed by the destructors name.

| This is a public function add.

| It returns sum of a and b.  

| Here we access the constructor using the scope resolution operator.

| a and b are private members.

| To access the private members we use x and y.

| In this we print '''Memory Deallocation.'''

| Here we create an object '''obj''' of class '''Addition'''.  

| Then we pass two arguments as '''3''' and '''4'''.

| This means '''a's''' value is '''3 '''and '''b's'''value is '''4.'''

| The constructor that has arguments is called '''parameterized constructor.'''

| Here we call the function '''add '''using the object''' obj'''.

|And we print the sum.  

| Now let us execute the program.

| Open the terminal window by pressing '''Ctrl, Alt and T''' keys simultaneously on your keyboard.

| To compile type, '''g++ space cons hyphen dest dot cpp space hyphen o space cons'''

| '''Press Enter'''  

| Type '''dot slash cons'''

| Press '''Enter'''

| The output is displayed as  

| '''Sum is 7''' and '''Memory Deallocation'''

| Come back ot our program.

| Note that our filename is '''default dot cpp'''

| If a '''constructor''' is not declared in the '''class, '''

| Then the '''compiler''' assumes a '''default constructor''' for the class.

| This is our header file as '''iostream.'''

| Then we have a and b declared as''' public.'''

| Here we have '''sub''' function.

| Here we access the default constructor using the''' scope resolution operator.'''

| In this we have defined a variable '''x.'''

| Here we create an '''object''' '''s''' of class '''subtraction.'''

| Then the result is stored in variable''' x.'''

| And here we print the difference.

| This is our '''return''' statement.

| Now let us execute the program.

| Come back to our terminal.

| Let us compile type '''g++ space default dot cpp space hyphen o space def'''

| '''Press Enter'''

 

| Type '''dot slash def'''

| '''Press Enter'''

| The output is return as

| '''Difference is 4'''

| Here you can see that we have passed the arguments within the function.

| And in our previous example we have passed the arguments within the '''Object.'''

| Now let us go back to our slides.

| Let us summarize, In this tutorial we learned,

| '''Constructors.''' eg. '''Addition'''

| '''Parameterized Constructor.''' eg. '''Addition obj (3, 4);'''

| '''Destructors''' eg.''' ~Addition'''

| '''Default Constructor.''' eg. '''Subtraction'''

| As an assignment, Create a class named '''Division.'''

| Create a constructor for the class.

| And Create a function '''divide''' which divides two given numbers.

| Watch the video available at the link shown below

| It summarises the Spoken Tutorial project.

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| This is Ashwini Patil from IIT Bombay signing off. Thank You for joining.