Ruby/C2/Ruby-Methods/English-timed

Time'	Narration
00.01	Welcome to the Spoken Tutorial on Ruby Methods.
00.05	In this tutorial we will learn
00.07	What is a method ?
00.09	Syntax for method and
00.11	We will Some examples
00.13	Here we are using Ubuntu Linux version 12.04 Ruby' 1.9.3
00.21	To follow this tutorial you must have knowledge of using Terminal and Text editor in Linux.
00.28	Let us now start with an introduction to methods.
00.31	A Method is a self-contained program executing a specific task.
00.37	Ruby method is very similar to functions in any other programming language.
00.42	Method name should begin with a lowercase letter.
00.45	Methods should be defined before calling them.
00.49	Let us see the syntax for Method
00.52	Methods are defined using the keyword def followed by the method name.
00.57	The arguments specify values that are passed to the method, to be processed.
01.02	ruby code section represents the body of the method that performs the processing.
01.09	The method body is enclosed by this definition on the top and the word end on the bottom
01.16	This is called as method with arguments.
01.19	Another syntax for method is
01.23	The keyword def followed by the method name and an empty argument list
01.28	ruby code section that represents the body of the method .
01.32	And the word end that marks end of method
01.36	This is called as method without arguments.
01.39	Let's see how to use a method.
01.42	I have already typed a program in the gedit editor.
01.46	Let me open it.
01.48	Please note that our filename is method hyphen without hyphen argument dot rb
01.55	I have saved the file inside the rubyprogram folder.
01.59	In this program we will calculate the sum of two numbers using method.
02.03	Let us go through the program.
02.05	Here we have declared a global variable a.
02.08	And we have initialized it by assigning value of 5.
02.13	Global variable names are prefixed with a dollar sign ($).
02.17	Global variables are accessible from anywhere in the Ruby program; regardless of where they are declared.
02.25	Here we have declared a method called add without any arguments.
02.31	Here we ask the user to enter the second number.
02.35	User will enter the value.
02.38	gets method gets the input from the console but in a string format.
02.44	So we need to convert it into integer, using to_i method.
02.50	The converted value is then stored in the variable b . b is a local variable.
02.56	It is available only to the method inside which it is declared.
03.01	Here we add the values of global variable a and variable b.
03.07	The result is then stored in variable sum.
03.10	Then we print the sum.
03.13	This shows a way of inserting a variable within a string.
03.18	Here the content of sum is returned as a string and is substituted into the outer string.
03.25	end marks the end of the method.
03.28	There are two types of methods.
03.31	User-defined method - that is our add method.
03.35	Pre-defined method - that is print, gets and to_i method.
03.42	Here we call our add method.
03.45	The addition operation will be performed and the result will be printed.
03.50	Now let us click on the Save. button.
03.53	This program will be saved in rubyprogram folder as mentioned earlier.
03.59	Now let us execute the program.
04.02	Open the terminal by pressing the Ctrl, Alt and T keys simultaneously.
04.07	A terminal window appears on your screen.
04.11	To execute the program, we need to go to the subdirectory rubyprogram.
04.16	So let's type cd space Desktop/rubyprogram and press Enter.
04.26	Now Type ruby space method hyphen without hyphen argument dot rb and press Enter
04.40	Enter the second number is displayed.
04.44	I will enter value as 4. type 4 and press enter
04.48	We get the output as - Sum of two numbers 5 and 4 is 9
04.53	Now let us see an example of method with arguments.
04.58	I have already typed this program in the gedit editor, let me open it.
05.03	Please note that our filename is method hyphen with hyphen argument dot rb
05.10	I have saved this file also inside the rubyprogram folder.
05.15	Let us go through the program.
05.18	Here we have declared a method called add. a,b are the arguments of the method add.
05.26	Here the values of a and b are added.
05.29	And the sum is returned to the method call.
05.31	end marks the end of method.
05.35	Here we are asking the user for input.
05.38	User will enter the values of a and b.
05.41	The values will be stored in variable a and b, respectively.
05.46	Here we call the add method
05.49	Then we pass the arguments as a and b.
05.52	The value returned by the method add , after performing the addition operation will be stored in c.
05.59	Here we print the sum which is store in c.
06.03	Lets execute this code. Go to the terminal.
06.07	Let us first clear the terminal. Type clear and press enter
06.14	We are already in the subdirectory rubyprogram.
06.17	Now, press the up arrow key twice to get the previous command.
06.22	Replace method hyphen without hyphen arguments dot rb with method hyphen with hyphen arguments dot rb
06.32	And Press Enter
06.35	Enter the values of a and b is displayed.
06.38	I will enter 8 and 9.
06.41	Type 8 and press Enter
06.43	Type 9 and press Enter
06.46	We get the output as
06.47	Sum of two numbers 8 and 9 is 17.
06.52	Now I will show you one important feature of Ruby method.
06.56	Let's go back to the program in the text editor.
06.59	Delete the keyword return.
07.02	Now click on Save button.
07.05	Let's execute the code.Go to the terminal.
07.09	Press the up arrow key to get the previous command and Press Enter.
07.14	Enter the values of a and b 'is displayed.
07.18	I will enter 10 and 15.
07.21	Type 10, press Enter Type 15 and press Enter
07.27	We get the output as
07.29	Sum of two numbers 10 and 15 is 25.
07.33	We can see that the program is executed without any error, even after deleting the keyword return.
07.40	This is because Ruby automatically returns the value calculated in the method.
07.46	The keyword return in method is optional in Ruby.
07.50	This brings us to the end of this Spoken Tutorial.
07.53	Let us switch back to slides
07.55	Let us summarize
07.57	In this tutorial we have learnt
07.59	About Methods
08.01	Syntax for Method without arguments
08.04	And Method with arguments
08.06	Returning value from method
08.08	As an assignment
08.10	Write a program,to calculate area of a square
08.13	by using method and
08.14	by getting the input from user
08.17	Watch the video available at the following link.
08.20	It summarises the Spoken Tutorial project.
08.23	If you do not have good bandwidth, you can download and watch it.
08.28	The Spoken Tutorial Project Team :
08.30	Conducts workshops using spoken tutorials
08.33	Gives certificates to those who pass an online test
08.36	For more details, please write to contact@spoken-tutorial.org
08.44	Spoken Tutorial Project is a part of the Talk to a Teacher project.
08.49	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
08.55	More information on this Mission is available at the below link
09.00	This is Afrin Pinjari from IIT Bombay, signing off.
09.04	Thank you for watching.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Priyacst, Sandhya.np14, Sneha