BASH/C3/Arrays-and-functions/English-timed

Time	Narration
00:01	Dear friends, welcome to the spoken tutorial on Arrays & functions.
00:07	In this tutorial, we will learn:
00:11	To pass an array to a function
00:14	Use of exit statement in a function
00:17	Use of return statement in a function
00:20	with the help of some examples.
00:24	To follow this tutorial, you should have knowledge of Shell Scripting.
00:29	You should also have knowledge of arrays and 'if' statement in BASH.
00:36	If not, for relevant tutorials, please visit our website which is as shown. http://www.spoken-tutorial.org
00:43	For this tutorial, I am using:
00:46	Ubuntu Linux 12.04 Operating System and
00:50	GNU BASH version 4.2
00:54	Please note, GNU Bash version 4 or above is recommended to practice this tutorial.
01:02	Let us first learn how to pass an array to a function and its usage.
01:09	Let me open a file function_(underscore)array dot sh.
01:15	This is the shebang line.
01:18	Our function name is array_(underscore) display.
01:22	Open curly brace opens the function definition.
01:27	The use of Dollar @(at-sign) was explained in previous tutorials in this series.
01:34	Basically, it is used to print all arguments passed to a function.
01:40	Dollar @ (at sign) within round brackets stores array elements in variable 'array'.
01:47	Dollar opening curly brace array within square bracket @(At-sign) closing curly brace.
01:55	This line of code displays all the elements of an array.
02:00	Dollar opening curly brace array within square brackets one closing curly brace.
02:08	This line of code displays the second element of the array.
02:14	operating_systems is declared with the elements "Ubuntu", "Fedora", "Redhat" and "Suse".
02:22	Here, array operating_systems is passed to the function array_display.
02:29	The syntax to pass an array to a function is function_name space dollar opening curly brace array_name within square brackets @(At sign) closing curly brace.
02:45	Come back to our program.
02:48	Similarly, colors is declared with the elements White, green, red and blue.
02:57	Here, array colors is passed to the function array_display.
03:02	Now let's save the file and go to the terminal.
03:07	Type: chmod space plus x space function underscore array dot sh
03:18	Press Enter.Type: dot slash function underscore array dot sh
03:25	Press Enter.
03:27	As we can see, array elements of 'operating_systems' and 'colors' are displayed.
03:33	And the second array element of 'operating_systems' and 'colors' are also displayed.
03:41	In Bash, 'exit' and 'return' statements give status code of a function or a program.
03:49	The return statement will return to the script from where it was called.
03:54	exit statement will end the entire script from where it is encountered.
04:01	Let us learn these 2 ways to return within a function.
04:06	Let me open a file 'return_exit.sh'.
04:12	This is the shebang line.
04:14	Function name is return_(Underscore)function .
04:18	Open curly brace opens the function definition.
04:22	This if statement compares two variables.
04:27	If the two variables are equal then commands in 'if' are executed.
04:33	This echo statement displays the message:
04:36	"This is return function".
04:39	return 0 moves the control from function to main program with status code 0(zero).
04:47	Note that the statements after return will not be executed in a function.
04:54	'fi' indicates the end of 'if' statement.
04:58	Here the function name is exit_(Underscore)function.
05:02	The 'if' statement here, compares two variables.
05:06	If the two variables are equal then the commands in 'if' are executed.
05:14	This echo statement displays the message "This is exit function" .
05:19	exit 0 will terminate the program.
05:23	'fi' indicates the end of this 'if' statement.
05:27	This is a function call with arguments 3 and 3.
05:33	This displays the message "We are in main program".
05:38	This is another function call with arguments 3 and 3.
05:44	This echo statement displays the message "This line is not displayed".
05:49	Note that exit will terminate the program.
05:53	Anything after exit will not be executed.
05:58	Save the file and go to the terminal.
06:00	Type: chmod space plus x space return underscore exit dot sh
06:09	Press Enter.
06:12	Type: dot slash return underscore exit dot sh
06:18	Press Enter.
06:20	The output displays the messages as shown.
06:24	Now, let us understand the flow of the program.
06:27	The control will be in main program which is the script itself.
06:33	The control goes to return_function because of the function call.
06:39	As the two variables are equal, it displays the message "This is return function".
06:47	Then it encounters return 0. And the control flows from function to the statement below the function call, in the main program.
06:59	Then it displays the message "We are in main program" .
07:03	After that, the control goes to exit_function because of the function call.
07:11	As the two variables are equal, it displays the message "This is exit function".
07:19	Then it encounters exit 0. This will terminate the program.
07:25	Any statement after exit will not be executed.
07:30	Also, the statement "This line is not displayed" will not be executed.
07:36	Hope the difference is clear to you.
07:39	Let us now summarize.
07:41	In this tutorial, we learnt:
07:44	To pass an array to a function
07:47	Use of exit statement in a function
07:50	Use of return statement in a function
07:53	with the help of some examples.
07:56	As an assignment-Write a program
07:58	where a function adds all the elements in an array. The function should display the sum of elements.
08:07	Make 2 function calls with array elements (1, 2, 3) and (4, 5, 6).
08:15	Watch the video available at the link shown below. http://spoken-tutorial.org/What_is_a_Spoken_Tutorial
08:19	It summarizes 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.Gives certificates to those who pass an online test.For more details, please write to contact@spoken-tutorial.org
08:45	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. More information on this mission is available at the link shown below. http://spoken-tutorial.org/NMEICT-Intro
09:04	The script has been contributed by FOSSEE and Spoken-Tutorial teams.
09:10	This is Ashwini Patil from IIT Bombay, signing off. Thank you for joining.

Contributors and Content Editors

Pratik kamble, Sandhya.np14