View source for Advanced-C++/C2/Function-Overloading-And-Overriding/English-timed

{| border=1
| '''Time'''
| '''Narration'''

|-
|00:01
| Welcome to the spoken tutorial on '''function Overloading and Overriding''' in '''C++.'''

|-
|00:09
| In this tutorial, we will learn,

|-
|00:11
|'''Function Overloading.'''

|-
|00:12
|'''Function Overriding.'''

|-
|00:14
|We will do this with the help of examples.

|-
|00:18
| To record this tutorial, I am using

|-
|00:21
|'''Ubuntu OS '''version 11.10

|-
|00:26
|'''g++ compiler '''v. 4.6.1

|-
|00:30
|Let us start with an introduction to '''function overloading.'''

|-
|00:34
|'''Function Overloading''' means two or more '''functions''' can have same name.

|-
|00:41
|The number of '''arguments''' and the '''data-type''' of the '''arguments''' will be different.

|-
|00:47
|When a '''function''' is called it is selected based on the argument list.

|-
|00:53
|Let us look at an example.

|-
|00:56
|I have already typed the code on the editor.

|-
|00:59
|In this program we will perform addition operations

|-
|01:03
|Note that our file name is '''overload.cpp'''

|-
|01:08
|Let me explain the code now.

|-
|01:10
|This is our '''header file''' as '''iostream.'''

|-
|01:13
|Here we are using the '''std namespace.'''

|-
|01:17
|Then we have '''add''' function defined as '''int.'''

|-
|01:21
|In this we have passed three arguments.

|-
|01:24
|'''Int a, int b''' and '''int c'''

|-
|01:28
|Then we perform addition of three numbers. And we '''return''' the '''value.'''

|-
|01:33
|Here we overload the function '''add.'''

|-
|01:36
|It is declared as''' float.'''

|-
|01:38
|We had pass two arguments '''float d'''  and '''float e'''

|-
|01:44
|Then we perform the addition operation on two numbers.

|-
|01:48
|This is our '''main''' function.

|-
|01:50
|In''' function''' '''main '''we declare the '''add''' '''function''' with different '''arguments'''.

|-
|01:56
|Then we declare the '''variables'''. 

|-
|01:58 
|Here we accept integer values from the user.

|-
|02:03
|Then we call the function '''add '''with three ''' arguments.''' 

|-
|02:07
|And store the result in variable''' sum.'''

|-
|02:09
|Here we print the result.

|-
|02:12
|Now here we accept '''floating point numbers''' from the user.

|-
|02:17
|Then we call the add function with two arguments. 

|-
|02:21
|And here we print the '''sum'''.

|-
|02:23
|And this is our '''return''' statement

|-
|02:26
|Now let us execute the program

|-
|02:29
|Open the terminal window by pressing '''Ctrl, Alt and T '''keys simultaneously on your keyboard.

|-
|02:38
|To execute type: '''g++ space overload dot cpp space hyphen o space over'''

|-
|02:49
|Press '''Enter'''

|-
|02:51
|Type '''dot slash over'''

|-
|02:53
|Press '''Enter'''

|-
|02:55
|It is displayed '''Enter three integers'''

|-
|02:58
|I will enter   '''10''', '''25''' and '''48'''

|-
|03:04
|The output is displayed as: '''Sum of integers is 83'''

|-
|03:09
|Now we see:  '''Enter two floating point numbers'''

|-
|03:13
|I will enter as: '''4.5''' and '''8.9'''

|-
|03:17
|Press '''Enter'''

|-
|03:19
|The output is displayed as: '''Sum of floating point numbers is 13.4'''

|-
|03:25 
|Now we will see '''function overriding'''.

|-
|03:29
|Let us switch back to our slides.

|-
|03:31
|Redefining a '''base class''' '''function''' in the derived class.

|-
|03:36
|The derived '''class function''' overrides the base class function.

|-
|03:40
|But the '''arguments''' passed are same.

|-
|03:44
|And the '''return-type''' is also same.

|-
|03:47
|Let us see an example

|-
|03:49
|Here is an example on '''function Overriding'''

|-
|03:53
|Note that our filename is '''override.cpp.'''

|-
|03:57
|Let us go through the code.

|-
|04:00 
|This is our header file as '''iostream'''

|-
|04:03
|Here we are using the''' std namespace.'''

|-
|04:06
|Then we have '''class arithmetic.'''

|-
|04:09
|In this we have declared integer variables as  as '''protected.'''

|-
|04:14
|Then we have '''function values''' declared as '''public'''.

|-
|04:18	
|In these we have passed two arguments '''int x''' and '''int y'''.

|-
|04:23
|Then we stored the value in '''a''' and '''b'''.

|-
|04:26
|Here we have '''virtual function''' as '''operations.'''

|-
|04:30
|In this we add the two numbers and print the '''sum.'''

|-
|04:34
|Here we close the class.

|-
|04:37
|Now we have '''class Subtract''' as '''derived class.'''

|-
|04:41
|This inherits the''' base class arithmetic.'''

|-
|04:45
|In this we calculate the difference of two numbers and we print the difference.

|-
|04:50 
|Now we have another '''derived class''' as '''Multiply.'''

|-
|04:54
|This also inherits''' base class arithmetic.'''

|-
|04:57
|In this we calculate the product of two numbers and display the product.

|-
|05:03
|Then we have '''class Divide '''this also inherits the''' base class arithmetic.'''

|-
|05:09
|In this we calculate the division of two numbers and  we display the division.

|-
|05:15
|Note that the return type of the function is same and the arguments passed are also  same.

|-
|05:23
|This is our '''main function.'''

|-
|05:26
|In this we create an''' object '''of ''' class arithmetic''' as '''p.'''

|-
|05:31
|'''arith '''is the pointer to the''' class arithmetic.'''

|-
|05:35
|Then we have''' subt object '''of''' class Subtract.'''

|-
|05:39
|'''mult object '''of''' class Multiply.'''

|-
|05:42
|And''' divd object ''' of ''' class Divide.'''

|-
|05:46
|Now here, '''p''' is set to the address of '''arith.

|-
|05:50
|Then we pass''' arguments '''as''' 30 '''and''' 12 '''in''' function values.'''

|-
|05:56
|Now we call the '''function operations.'''

|-
|05:59
|This will perform the addition operation.

|-
|06:02
|Here we set '''subt''' to the address of '''arith.'''

|-
|06:07
|And we pass''' 42 '''and''' 5 '''as''' arguments.'''

|-
|06:11
|Again we call''' function operations.'''

|-
|06:14
|This will perform subtraction of two numbers.

|-
|06:18
|Now,  here we set '''mult''' to the address of '''arith.'''

|-
|06:22
|And we pass  ''' 6 '''and''' 5''' as argument

|-
|06:26
|We call '''function operations.'''

|-
|06:29
|This will perform multiplication of two numbers.

|-
|06:33
|Atlast we set '''divd''' to the address of '''arith''' And we pass  '''6''' and '''3''' as '''arguments.''' 

|-
|06:41
|Now we  call operations '''functions'''

|-
|06:44
|This will perform division of two numbers.

|-
|06:48
|And this is our '''return statement.'''

|-
|06:50
|Let us execute the program. Switch back to our terminal.

|-
|06:54
|Type:  '''g++ space override dot cpp  space hyphen o space over2'''

|-
|07:04
|Press '''Enter'''

|-
|07:06
|Type: '''dot slash over2'''

|-
|07:09
|Press '''Enter'''

|-
|07:11
|The output is displayed as: 

|-
|07:13
|'''Addition of two numbers is 42'''

|-
|07:16
|'''Difference of two numbers is 37'''

|-
|07:19
|'''Product of two numbers is 30''' and '''Division of two numbers is 2'''

|-
|07:25
|Let us switch back to our slides.

|-
|07:27
|Let us see the difference of '''overloading''' and '''overriding'''.

|-
|07:31
|'''Overloading''' can occurs without inheritance.

|-
|07:35
|'''Overriding''' occurs when one class is inherited from another.

|-
|07:41
|In '''overloading''' the arguments and the return-type must differ.

|-
|07:46
|In '''overriding''' the arguments and the return type must be same.

|-
|07:51
|In '''overloading''' the function name is same.

|-
|07:55
|But it behaves differently depending on the arguments passed to them. 

|-
|08:01
|In '''overriding''' the function name is same.

|-
|08:05
|'''Derived class '''function can perform different operations from the base class. 

|-
|08:11
| Let us summarize:

|-
|08:13
|In this tutorial learnt

|-
|08:15
|'''Function overloading.'''

|-
|08:16
|'''eg. int add''' with three different arguments  and

|-
|08:21
|'''float add''' with two different arguments.

|-
|08:24
|'''Function Overriding.'''

|-
|08:26
|'''eg. virtual int operations ()''' and '''int operations ()'''

|-
|08:31
|functions with the same argument and same return type and difference between both.

|-
|08:38
|As an assignment 

|-
|08:39
|Write a program that will calculate the area of rectangle, square and circle 

|-
|08:46
|Using '''function overloading.'''
 
|-
|08:48
|Watch the video available at the link shown below

|-
|08:52
|It summarizes the Spoken Tutorial project 

|-
|08:55
|If you do not have good bandwidth, you can download and watch it

|-
|08:59
|The Spoken Tutorial Project Team 

|-
|09:02
|Conducts workshops using spoken tutorials 

|-
|09:05
|Gives certificates to those who pass an online test 

|-
|09:09
|For more details, please write to,

|-
|09:12
|contact@spoken-tutorial.org

|-
|09:16
|Spoken Tutorial Project is a part of the Talk to a Teacher project

|-
|09:20
|It is supported by the National Mission on Education through ICT, MHRD, Government of India

|-
|09:27
|More information on this Mission is available at the link shown below

|-
| 09:32
| This is Ashwini Patil from IIT Bombay signing off

|-
|09:36
|Thank You for joining. 

|}