Difference between revisions of "BASH/C3/Recursive-function/English-timed"

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Revision as of 15:07, 12 December 2014

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.
05:39 It summarises the Spoken Tutorial project.
05:43 If you do not have good bandwidth, you can download and watch it.
05:47 The Spoken Tutorial Project Team Conducts workshops using spoken tutorials
05:53 Gives certificates to those who pass an online test
05:58 For more details, please write to contact@spoken-tutorial.org
06:06 Spoken Tutorial Project is a part of the Talk to a Teacher project.
06:10 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
06:18 More information on this Mission is available at the link shown below http://spoken-tutorial.org\NMEICT-Intro
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