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

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 version 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 have passed 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	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 file name 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 this, we have passed two arguments- int x and int y.
04:23	Then we stored the values 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 arguments.
06:26	We call the function operations().
06:29	This will perform the multiplication of two numbers.
06:33	At last, we set divd to the address of arith and we pass 6 and 3 as arguments.
06:41	Now we call the operations() function.
06:44	This will perform the division of two numbers.
06:48	And this is our return statement.
06:50	Let us execute the program. Switch back to the 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 occur 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, we 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	Then 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.
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08:59	The Spoken Tutorial Project team:
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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.

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Gaurav, PoojaMoolya, Pratik kamble, Ranjana, Sandhya.np14