BASH/C3/Recursive-function/English-timed

Time	Narration
00:01	Dear friends, welcome to the spoken tutorial on Recursive function.
00:07	In this tutorial, we will learn
00:10	What is a Recursive function?
00:12	With the help of some examples
00:15	To follow this tutorial, you should have knowledge of Shell Scripting in BASH.
00:20	If not, for relevant tutorials please visit our website which is as shown,http://www.spoken-tutorial.org
00:27	For this tutorial I am using
00:29	Ubuntu Linux 12.04 Operating System
00:33	and GNU BASH version 4.2
00:37	Please note, GNU Bash version 4 or above is recommended for practice
00:44	Let us see what a recursive function is.
00:48	A recursive function is one which calls itself
00:52	Recursion is a useful technique for simplifying complex algorithms
00:59	Let me open a file named factorial.sh
01:04	I have typed the code in this file.
01:07	This is the shebang line.
01:10	factorial is the function name.
01:12	Inside this, we print a message “Inside factorial function”
01:19	This statement reads user's input and stores the value in variable 'n'
01:26	Here we have if-else condition.
01:30	If condition checks whether the value of 'n' is equal to zero.
01:36	If true, it will display the message "factorial value of n is 1".
01:42	Here is the else part of the if statement.
01:46	It calls the factorial function.
01:50	And fi is the end of the if-else statement.
01:55	Let us run the file factorial.sh.
01:59	Open the terminal using CTRL+ALT+T keys simultaneously on your keyboard.
02:07	Type: chmod space plus x space factorial dot sh
02:15	Press Enter.
02:17	Type dot slash factorial.sh
02:21	Press Enter.
02:24	We see "Enter the number".
02:26	I will enter 0.
02:29	The output is displayed as:
02:31	factorial value of 0 is 1
02:35	Now press the uparrow key. Recall the previous command.
02:40	Press Enter.
02:42	This time, I will enter 5 .
02:45	Now the output is displayed as:
02:47	Inside factorial function.
02:51	Let us add some more logic to the factorial function.
02:56	We will calculate the factorial of a number.
03:01	Come back to our code.
03:03	Now let us replace, the echo statement inside the factorial function with the code block.
03:10	Click on Save
03:13	temp is a variable and stores the value entered by user.
03:19	If condition checks whether the variable value is equal to 1.
03:25	If true, it will print 1.
03:29	This is the else part of the if statement.
03:33	This reduces one from the temp variable value.
03:37	And stores the result in a variable 'f'.
03:42	Variable f stores the output of factorial function.
03:46	This is a recursive call.
03:50	Value of variable f and temp is multiplied and stored in f.
03:57	Then we print the value of f.
04:00	End of if-else statement and function.
04:05	Now come back to our slides.
04:08	Let us understand the flow of the program.
04:12	# The value of n is taken from the user i.e. n
04:17	# If the value entered is equal to zero, then it prints a message
04:24	# Else it goes to the function factorial
04:29	# Here, if the value is equal to one, then it prints value as one
04:36	# If not, it makes a recursive call until the value is equal to one
04:44	# Then, all the values are multiplied and displayed
04:49	Now come back to our terminal.
04:52	Press the uparrow key.
04:54	Recall the previous command ./factorial.sh
04:58	Press Enter.
05:00	Now I will enter 5 as the input value.
05:05	We get the factorial of number 5.
05:08	That is 120.
05:11	We can see the flow of the program on terminal. Analyse and trace the flow of the program.
05:18	Come back to our slides.
05:20	Let us summarise.
05:21	In this tutorial we have learnt,
05:23	Recursive function
05:25	With the help of some examples
05:28	As an assignment.
05:29	Write a program where the recursive function calculates the sum of N numbers
05:36	Watch the video available at the link shown below.
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06:24	The script has been contributed by FOSSEE and Spoken-Tutorial teams.
06:29	This is Ashwini Patil signing off.
06:33	Thank you for joining.

Contributors and Content Editors

Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14