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

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| '''What is a Recursive''' function
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| 'what is a Recursive' function
  
 
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|  '''Recursion''' is a useful technique for simplifying complex algorithms.
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|  '''Recursion''' is a useful technique for simplifying complex '''algorithm'''s.
  
 
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|  '''factorial '''is the '''function''' name.  
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|  '''factorial() '''is the '''function''' name.  
  
 
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|  This statement reads user's '''input''' and stores the value in variable 'n'.
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|  This statement reads user's '''input''' and stores the '''value''' in variable 'n'.
  
 
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|  Here, we have '''if-else condition.'''
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|  Here, we have ''''if-else' condition.'''
  
 
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|  Here is the '''else '''part of the '''if '''statement.
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|  Here is the ''''else' '''part of the ''''if' '''statement.
  
 
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| 01:46
 
| 01:46
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| It calls the '''factorial function.'''
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| It calls the ''''factorial' function.'''
  
 
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| And '''fi '''is the end of the '''if-else''' statement.
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| And ''''fi' '''is the end of the ''''if-else'''' statement.
  
 
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| Let us '''run''' the file''' factorial.sh.'''
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| Let us '''run''' the file "factorial.sh".  
  
 
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| Open the '''terminal''' using '''CTRL+ALT+T '''keys simultaneously on your keyboard.
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| Open the '''terminal''' using '''CTRL+ALT''' and '''T '''keys simultaneously on your keyboard.
  
 
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| Type '''dot slash factorial.sh'''
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| Type: '''dot slash factorial.sh'''
  
 
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|  We see '''"Enter the number"'''.
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|  We see '''"Enter the number:" '''.
  
 
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| 02:26
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| I will enter '''0'''.
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| I will enter 0.
  
 
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|  The output is displayed as:
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|  The '''output''' is displayed as:
  
 
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| '''factorial value of 0 is 1'''
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| '''"factorial value of 0 is 1"'''.
  
 
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| This time, I will enter''' 5 '''.
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| This time, I will enter 5.
  
 
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| '''Inside factorial function.'''
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| '''"Inside factorial function".'''
  
 
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|  02:51
 
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|  Let us add some more logic to the '''factorial function.'''
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|  Let us add some more logic to the ''''factorial' function.'''
  
 
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|  Now let us replace the '''echo statement''' inside the '''factorial function''' with the '''code block'''.
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|  Now, let us replace the '''echo''' statement "Inside the factorial function" with the '''code block'''.
  
 
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|  '''If condition''' checks whether the variable value is equal to '''1'''.
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|  ''''If'''' condition checks whether the variable value is equal to 1.
  
 
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| and stores the result in a variable ''''f'.'''
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| and stores the result in a variable 'f'.
  
 
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|  '''Variable f '''stores the '''output''' of '''factorial function.'''
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|  Variable 'f' stores the '''output''' of ''''factorial' function.'''
  
 
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|  Value of variable '''f''' and '''temp''' is multiplied and stored in '''f'''.
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|  Value of variable 'f' and '''temp''' are multiplied and stored in 'f'.
  
 
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| Then we '''print''' the value of '''f.'''
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| Then we '''print''' the value of 'f'.
  
 
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|  Now come back to our '''slides.'''
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|  Now, come back to our '''slides.'''
  
 
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|  # The value of '''n''' is taken from the user i.e. '''n'''.
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|  # The value of 'n' is taken from the user i.e. 'n'.
  
 
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| # Else it goes to the function '''factorial'''.
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| # Else it goes to the '''function''' '''factorial'''.
  
 
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| In this tutorial, we have learned
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| In this tutorial, we learned
  
 
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|  05:29
 
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| write a program where the '''recursive function''' calculates the sum of''' N '''numbers.
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| write a program where the '''recursive function''' calculates the sum of 'N' numbers.
  
 
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|  The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials;
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|  The Spoken Tutorial Project Team: *Conducts workshops using spoken tutorials;
  
 
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|-
 
|  05:53
 
|  05:53
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| Gives certificates to those who pass an online test.
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|* Gives certificates to those who pass an online test.
  
 
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| 06:29  
 
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| This is Ashwini Patil. signing off.
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| This is Ashwini Patil, signing off.
  
 
|-
 
|-

Revision as of 11:06, 15 July 2015

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 and 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 up-arrow 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 are 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 up-arrow 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. Analyze and trace the flow of the program.
05:18 Come back to our slides.
05:20 Let us summarize.
05:21 In this tutorial, we learned
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 summarizes 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

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