Difference between revisions of "Ruby/C2/Variables-in-Ruby/English-timed"

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(Created page with ' {| border=1" ! Visual Clue ! Narration |- | 00.03 | Welcome to the Spoken Tutorial onVariables in '''Ruby''' |- | 00.07 | In this tutorial we will learn |- | 00.09 …')
 
 
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{| border=1
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{| border=1"
+
|| '''Time'''
−
! Visual Clue
+
|| '''Narration'''
−
!  Narration  
+
  
 
|-
 
|-
−
|  00.03
+
|  00:02
−
|   Welcome to the Spoken Tutorial onVariables in '''Ruby'''  
+
| Welcome to the '''Spoken Tutorial''' on '''Variables in Ruby'''.
  
 
|-
 
|-
−
|  00.07
+
|  00:06
−
| In this tutorial we will learn
+
| In this tutorial, we will learn:
  
 
|-
 
|-
−
|  00.09
+
|  00:09
−
| What is a variable?
+
| What is a variable? Dynamic typing in '''Ruby'''
 +
 
 
|-
 
|-
−
|  00.11
+
|  00:13
−
| Dynamic typing in '''Ruby'''
+
| Declaring a variable
 +
 
 
|-
 
|-
−
|  00.13
+
|  00:15
−
| Declaring a variable
+
| Converting variable types
 +
 
 
|-
 
|-
−
|  00.15
+
|  00:18 
−
| Converting variable types
+
| What is variable's scope?
 +
 
 
|-
 
|-
−
|  00.18 
+
|  00:20
−
|  What is variable's scope?
+
| Types of variables.
−
|-
+
−
|  00.20
+
−
| Types of variables
+
  
 
|-
 
|-
−
|  00.23
+
|  00:23
−
|  Here we are using '''Ubuntu''' Linux version 12.04   '''Ruby''' 1.9.3
+
|  Here, we are using: '''Ubuntu Linux''' version '''12.04''', '''Ruby 1.9.3'''
−
 
+
−
 
+
  
 
|-
 
|-
−
|  00.32
+
|  00:32
−
|  To follow this tutorial you must have knowledge of using''' Terminal''' in '''Linux.'''
+
|  To follow this tutorial, you must have the knowledge of using''' Terminal''' in '''Linux.'''
−
 
+
  
 
|-
 
|-
−
|  00.38
+
|  00:38
−
| You must also be familiar with '''irb'''
+
| You must also be familiar with '''"irb"'''.
−
 
+
  
 
|-
 
|-
−
|  00.41
+
|  00:41
−
| If not, for relevant tutorials, please visit our website
+
| If not, for relevant tutorials, please visit our website.
−
 
+
−
 
+
−
 
+
  
 
|-
 
|-
−
|  00.47
+
|  00:47
−
|  Now I will explain what a variable is.
+
|  Now, I will explain you what a '''variable''' is.
−
 
+
  
 
|-
 
|-
−
|  00.51
+
|  00:50
 
|  Variable is used to store a value.
 
|  Variable is used to store a value.
 +
 
|-
 
|-
−
|  00.55
+
|  00:54
 
|  Variable is a reference that can be assigned.
 
|  Variable is a reference that can be assigned.
 +
 
|-
 
|-
−
|  00.59
+
|  00:58
−
|  Please note that '''Ruby '''variables are''' case sensitive.'''
+
|  Please note that '''Ruby variables''' are '''case sensitive.'''
  
 +
|-
 +
| 01:04
 +
|  Variable names should be meaningful.
  
−
 
−
|-
 
−
| 01.04
 
−
|  Variable names should be '''meaningful'''.
 
 
|-
 
|-
−
|01.07  
+
|01:07  
−
|  Variable name may only contain lowercase letters, numbers and underscores.  Ex : first_name
+
|  Variable name may only contain lowercase letters, numbers, underscores.  Ex : first_name
−
 
+
−
 
+
  
 
|-
 
|-
−
|  01.20
+
|  01:20
−
|  Now''' '''let us see what is dynamic typing
+
|  Now, let us see what is '''dynamic typing'''.
  
 
|-
 
|-
−
|  01.24
+
|  01:23
 
|  '''Ruby''' is a dynamic typed language.
 
|  '''Ruby''' is a dynamic typed language.
 
|-
 
|-
−
|  01.28
+
|  01:27
−
|  It means that you '''don't''' need to declare '''datatype''' while creating a variable.
+
|  It means that you don't need to declare datatype while creating a variable.
  
 
|-
 
|-
−
|  01.34
+
|  01:34
−
|  '''Ruby interpreter '''determines the data type at the time of assignment.
+
|  '''Ruby interpreter '''determines the datatype at the time of assignment.
−
 
+
−
 
+
  
 
|-
 
|-
−
|  01.39
+
|  01:39
−
|  Now let us see how to declare a variable in '''Ruby.'''
+
|  Now, let us see how to declare a variable in Ruby.
  
 
|-
 
|-
−
|  01.45
+
|  01:45
−
|  Open the terminal by pressing '''Ctrl,Alt''' and''' T '''keys simultaneously.
+
|  Open the '''terminal''' by pressing '''Ctrl, Alt''' and''' T '''keys simultaneously.
−
 
+
  
 
|-
 
|-
−
|  01.51  
+
|  01:51  
−
| A terminal window appears on your screen.
+
| A '''terminal window''' appears on your screen.
  
 
|-
 
|-
−
| 01.55
+
| 01:55
−
|  Type''' ''''''irb'''
+
|  Now, type "irb" and
  
 
|-
 
|-
−
|  01.57
+
|  01:57
−
| Press '''Enter '''to launch '''Interactive Ruby'''
+
| press '''Enter '''to launch '''Interactive Ruby'''.
  
 
|-
 
|-
−
|  02.02
+
|  02:02
−
|  Now type '''var1''' equal to '''10  and'''Press '''Enter'''
+
|  Now, type: '''var1''' equal to 10  and press '''Enter'''.
  
 
|-
 
|-
−
|  02.09
+
|  02:09
−
|  Here we have declared a variable '''var1''' and assigned a value '''10 '''to it'''.'''
+
|  Here, we have declared a variable '''var1''' and assigned a value '''10 ''' to it.
  
 
|-
 
|-
−
| 02.15
+
| 02:15
−
|  Let's check whether the datatype allotted by the interpreter is  '''integer '''or not''' . '''
+
|  Let's check whether the datatype allotted by the interpreter is  integer or not.
−
 
+
  
 
|-
 
|-
−
| 02.21
+
| 02:21
−
|  So, type '''var1 '''dot '''kind''' underscore '''of '''question mark '''Integer'''and press '''Enter'''
+
|  So, type: '''var1''' dot '''kind'''_(underscore)'''of '''(?)question mark '''Integer''' and press '''Enter'''.
  
 
|-
 
|-
−
|  02.37
+
|  02:37
−
|  We will get the output as '''true.'''
+
|  We get the output as "true".
  
 
|-
 
|-
−
|  02.40
+
|  02:39
−
|  In''' Ruby''' you can dynamically change the variable type.
+
|  In''' Ruby''', you can dynamically change the variable type.
  
 
|-
 
|-
−
|  02.44
+
|  02:44
 
| To do so, just assign a new value to it.
 
| To do so, just assign a new value to it.
  
 
|-
 
|-
−
|  02.48
+
|  02:47
 
| Let's do this by assigning a '''string''' value to variable '''var1.'''
 
| Let's do this by assigning a '''string''' value to variable '''var1.'''
  
 
|-
 
|-
−
|  02.53
+
|  02:53
−
|   Type '''var1''' equal to within double quote '''hello'''and   press Enter
+
| Type: '''var1''' equal to within double quotes '''hello''' and press '''Enter'''.
  
 
|-
 
|-
−
| 03.03  
+
| 03:02  
−
| Let's verify the variable type assigned  
+
| Let's verify the variable type assigned.
  
 
|-
 
|-
−
|  03.06
+
|  03:06
−
| Type  '''var1''' dot '''class '''
+
| Type: '''var1''' dot '''class '''.
  
 +
|-
 +
|  03:12
 +
| '''Class''' method tells us what class of variable it is. Now press ''' Enter'''.
  
 
|-
 
|-
−
|  03.12
+
|  03:20
−
| Class method tells us what class of variable it is. Now  Press''' Enter'''
+
| We get the output as "String".
  
 
|-
 
|-
−
| 03.20
+
| 03:23
−
|  We get the output as '''string'''
+
|  Ruby has automatically changed the variable type from '''integer''' to '''string'''.
  
 
|-
 
|-
−
| 03.20
+
|   03:29
−
|  '''Ruby '''has automatically changed the variable type from '''integer''' to '''string'''
+
|  We will now learn how to convert a variable value to different type.
  
 
|-
 
|-
−
|   03.30
+
| 03:35
−
| | We will now learn how to convert a variable value to different type
+
| Let's switch back to slide.
  
 
|-
 
|-
−
|  03.35
+
|  03:38
−
| Lets switch back to slides
+
| Ruby variable classes have methods to convert their value to a different type.
  
 +
|-
 +
|  03:45
 +
|  ''''to_i'''' method is used to convert a variable to '''integer'''.
  
 
|-
 
|-
−
|  03.39
+
|  03:51
−
| '''Ruby''' variable classes have methods to convert their value to a different type
+
| ''''to_f'''' method is used to convert a variable to '''floating point value'''.
  
 
|-
 
|-
−
|  03.45
+
|  03:57
−
|  '''to_i '''method is used to convert a variable to '''integer'''
+
|  ''''to_s'''' method is used to convert a variable to''' string'''.  
−
|-
+
−
|  03.51
+
−
|  '''to_f '''method is used to convert a variable to '''floating point value'''
+
−
|-
+
−
|  03.57
+
−
|  '''to_s''' method is used to convert a variable to''' string'''
+
−
 
+
  
 
|-
 
|-
−
|  04.03
+
|  04:03
−
| The '''to _''' '''s()''' method takes number base as an argument.
+
| ''''to _s'''' method takes '''number base''' as an '''argument'''.
  
 
|-
 
|-
−
|  04.08
+
|  04:08
 
| The conversion depends on this number base.  
 
| The conversion depends on this number base.  
  
 
|-
 
|-
−
| 04.12
+
| 04:12
−
|  Now let us try out these methods.
+
|  Now, let us try out these methods.
  
 
|-
 
|-
−
|  04.15
+
|  04:15
−
| Go to the''' terminal'''  Lets clear the terminal first
+
| Go to the''' terminal'''. Let's clear the terminal first.
  
 
|-
 
|-
−
|  04.21
+
|  04:21
−
| Press Ctrl,l to clear the '''irb '''console  
+
| Press '''Ctrl, L''' to clear the '''irb '''console.
−
 
+
  
 
|-
 
|-
−
| 04.25
+
| 04:25
−
| Now  Type '''y '''equal to '''20'''  and Press''' '''Enter
+
| Now, type: '''y '''equal to '''20'''  and press '''Enter'''.
  
 
|-
 
|-
−
|  04.32
+
|  04:32
−
|  Here we have declared a variable called''' y''' and assigned a value '''20''' to it.
+
|  Here, we have declared a variable called 'y' and assigned a value '''20''' to it.
  
 
|-
 
|-
−
|  04.40
+
|  04:39
−
| We will now convert '''y''' to a floating point value using '''to '''underscore''' f''' method
+
| We will now convert 'y' to a '''floating point value''' using '''to underscore f''' method.
  
 
|-
 
|-
−
|  04.47
+
|  04:47
−
|  Type '''y '''dot '''to '''underscore '''f''' and  Press '''Enter'''
+
|  Type: '''y '''dot '''to underscore f''' and  press '''Enter'''.
  
 
|-
 
|-
−
|  04.55
+
|  04:55
−
| We will get the value as float'''.'''
+
| We get the value as '''float'''.
  
 
|-
 
|-
−
|  04.58
+
|  04:57
−
|  Now Type '''y '''dot '''to '''underscore '''s. and''' Press '''Enter'''
+
|  Now, type: '''y '''dot '''to underscore s''' and press '''Enter'''.
  
 
|-
 
|-
−
| 05.06
+
| 05:06
−
|  We will get output '''20 '''within double quotes
+
|  We get the output as 20, within double quotes.
  
 
|-
 
|-
−
|  05.11
+
|  05:10
−
| To convert variable '''y''' in binary form give number base as '''2''' in '''to_s''' method
+
| To convert variable 'y' in binary form, give '''number base''' as '''2''' in the '''to_s''' method.
  
 
|-
 
|-
−
|  05.18
+
|  05:18
−
| Press up arrow key to get the previous command  
+
| Press the up-arrow key to get the previous command.
  
 
|-
 
|-
−
|  05.22
+
|  05:22
−
|  Now type opening bracket 2 closing bracket and  press '''Enter'''
+
|  Type: opening bracket 2 closing bracket and  press '''Enter'''.
  
 
|-
 
|-
−
|  05.30
+
|  05:29
−
| We will get the output''' 10100 '''in the binary form
+
| We get the output in the '''binary''' form.
  
 
|-
 
|-
−
| 05.33
+
| 05:33
−
|   Similarly you can convert variable '''y''' to '''octal''' or '''hexadecimal''' form  
+
| Similarly, you can convert variable 'y' to '''octal''' or '''hexadecimal''' form  
  
 
|-
 
|-
−
|  05.39
+
|  05:39
−
| By changing the number base to 8 or 16.
+
| by changing the number base to '''8''' or '''16'''.
  
 
|-
 
|-
−
|  05.44
+
|  05:44
−
|  Let us switch back to our slide
+
|  Let us switch back to our '''slide'''.
  
 
|-
 
|-
−
|  05.48
+
|  05:47
 
|  We will now learn what is a '''variable scope'''.
 
|  We will now learn what is a '''variable scope'''.
  
 +
|-
 +
|  05:51
 +
| '''Scope''' defines- where in a program, a variable is accessible.
  
 
|-
 
|-
−
|  05.52
+
|  05:56
−
| '''Scope''' defines where in a program a variable is accessible.
+
| '''Ruby''' has four types of variable scopes:
  
 +
|-
 +
|  06:00
 +
| Local,  Global
  
 
|-
 
|-
−
|  05.56
+
|  06:02
−
| '''Ruby''' has four types of variable scope:
+
|Instance and
−
 
+
−
* '''Local'''
+
−
* '''Global'''
+
−
* '''Instance '''
+
−
* '''Class '''
+
  
 +
|-
 +
|  06:04
 +
| Class.
  
 +
|-
 +
|  06:06
 +
|  Each variable type is declared by using a special character at the beginning of the variable name.
  
 
|-
 
|-
−
| 06.06
+
| 06:14
−
| Each variable type is declared by using a special character
+
| '$' represents '''global''' variable.
  
 
|-
 
|-
−
| 06.11
+
| 06:18
−
| At the beginning of the variable name
+
| Lower case letters and underscore represent a '''local''' variable.
−
 
+
  
 
|-
 
|-
−
|   06.14
+
| 06:25
−
| '''$ '''represents '''global''' variable  
+
| '@' represents an '''instance''' variable.
  
 
|-
 
|-
−
| 06.18
+
| 06:29
−
| Lower case letters and  underscore represents a '''local''' variable
+
| Two '@@' symbols represent a '''class''' variable.
  
 
|-
 
|-
−
|  06.25
+
|  06:33
−
| '''@''' represents an '''instance''' variable
+
| Upper case letters represent a '''constant'''.
  
 
|-
 
|-
−
| 06.29
+
| 06:37
−
| Two''' @@''' represents a '''class''' variable
+
| We will learn in detail, about this, in another tutorial.
  
 
|-
 
|-
−
| 06.33
+
| 06:42
−
| Upper case letters represents a '''constant'''
+
| This brings us to the end of this Spoken Tutorial. Let us summarize.
−
 
+
  
 
|-
 
|-
−
| 06.37
+
| 06:48
−
| We will learn in detail about this in another tutorial.
+
| In this tutorial, we have learnt:
  
 
|-
 
|-
−
| 06.42
+
| 06:51
−
| This brings us to the end of this Spoken Tutorial. Let us summarises
+
|To declare a variable, e.g. var1=10
  
 
|-
 
|-
−
| 06.49
+
| 06:56
−
| In this tutorial we have learnt
+
| Changing a variable type using 'to_f' and 'to_s' methods
  
 
|-
 
|-
−
|  06.51
+
|  07:04
−
|  To declare a variable  eg var1=10
+
| Different variable '''scope'''s.
−
|-
+
−
|  06.56
+
−
|  Changing variable type using to_f, to_s methods
+
−
|-
+
−
|  07.04
+
−
| Different Variable '''scope'''
+
−
 
+
−
 
+
  
 
|-
 
|-
−
|  07.07
+
|  07:06
−
| As an assignment
+
| As an assignment,
  
 
|-
 
|-
−
|  07.08
+
|  07:08
−
| Declare a variable and convert it to '''octal''' and '''hexadecimal''' form
+
| declare a variable and convert it to '''octal''' and '''hexadecimal''' form.
−
 
+
−
 
+
−
 
+
  
 
|-
 
|-
−
|  07.14
+
|  07:14
 
|  Watch the video available at the following link.
 
|  Watch the video available at the following link.
−
 
  
 
|-
 
|-
−
|  07.17
+
|  07:17
−
| It summarises the Spoken Tutorial project.
+
| It summarizes the Spoken Tutorial project.
  
 
|-
 
|-
−
|  07.20
+
|  07:20
 
| If you do not have good bandwidth, you can download and watch it.  
 
| If you do not have good bandwidth, you can download and watch it.  
  
 
|-
 
|-
−
|  07.25
+
|  07:24
−
|  The Spoken Tutorial Project Team :
+
|  The Spoken Tutorial project team :
−
 
+
  
 
|-
 
|-
−
|  07.27
+
|  07:27
−
| Conducts workshops using spoken tutorials  
+
| Conducts workshops using spoken tutorials.
  
 
|-
 
|-
−
|  07.30
+
|  07:30
−
| Gives certificates to those who pass an online test  
+
| Gives certificates to those who pass an online test.
  
 
|-
 
|-
−
|  07.34
+
|  07:34
−
| For more details, please write to contact at spoken hyphen tutorial dot org
+
| For more details, please write to: contact @ spoken hyphen tutorial dot org.
  
 
|-
 
|-
−
|  07.41
+
|  07:41
−
| Spoken Tutorial Project is a part of the Talk to a Teacher project.
+
| '''Spoken Tutorial''' project is a part of the '''Talk to a Teacher''' project.
  
 
|-
 
|-
−
|  07.46
+
|  07:45
 
| It is supported by the National Mission on Education through ICT, MHRD, Government of India.
 
| It is supported by the National Mission on Education through ICT, MHRD, Government of India.
  
 
|-
 
|-
−
|  07.52
+
|  07:51
−
| More information on this Mission is available at:  spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
+
| More information on this mission is available at the below link.
  
 
|-
 
|-
−
|  07.57
+
|  07:57
−
| This is Afrin Pinjari from IIT Bombay, signing off.
+
| This is Afrin Pinjari from '''IIT Bombay''', signing off. Thank you for watching.
−
 
+
−
Thank you for watching.
+
  
 
|}
 
|}

Latest revision as of 12:00, 10 March 2017

Time Narration
00:02 Welcome to the Spoken Tutorial on Variables in Ruby.
00:06 In this tutorial, we will learn:
00:09 What is a variable? Dynamic typing in Ruby
00:13 Declaring a variable
00:15 Converting variable types
00:18 What is variable's scope?
00:20 Types of variables.
00:23 Here, we are using: Ubuntu Linux version 12.04, Ruby 1.9.3
00:32 To follow this tutorial, you must have the knowledge of using Terminal in Linux.
00:38 You must also be familiar with "irb".
00:41 If not, for relevant tutorials, please visit our website.
00:47 Now, I will explain you what a variable is.
00:50 Variable is used to store a value.
00:54 Variable is a reference that can be assigned.
00:58 Please note that Ruby variables are case sensitive.
01:04 Variable names should be meaningful.
01:07 Variable name may only contain lowercase letters, numbers, underscores. Ex : first_name
01:20 Now, let us see what is dynamic typing.
01:23 Ruby is a dynamic typed language.
01:27 It means that you don't need to declare datatype while creating a variable.
01:34 Ruby interpreter determines the datatype at the time of assignment.
01:39 Now, let us see how to declare a variable in Ruby.
01:45 Open the terminal by pressing Ctrl, Alt and T keys simultaneously.
01:51 A terminal window appears on your screen.
01:55 Now, type "irb" and
01:57 press Enter to launch Interactive Ruby.
02:02 Now, type: var1 equal to 10 and press Enter.
02:09 Here, we have declared a variable var1 and assigned a value 10 to it.
02:15 Let's check whether the datatype allotted by the interpreter is integer or not.
02:21 So, type: var1 dot kind_(underscore)of (?)question mark Integer and press Enter.
02:37 We get the output as "true".
02:39 In Ruby, you can dynamically change the variable type.
02:44 To do so, just assign a new value to it.
02:47 Let's do this by assigning a string value to variable var1.
02:53 Type: var1 equal to within double quotes hello and press Enter.
03:02 Let's verify the variable type assigned.
03:06 Type: var1 dot class .
03:12 Class method tells us what class of variable it is. Now press Enter.
03:20 We get the output as "String".
03:23 Ruby has automatically changed the variable type from integer to string.
03:29 We will now learn how to convert a variable value to different type.
03:35 Let's switch back to slide.
03:38 Ruby variable classes have methods to convert their value to a different type.
03:45 'to_i' method is used to convert a variable to integer.
03:51 'to_f' method is used to convert a variable to floating point value.
03:57 'to_s' method is used to convert a variable to string.
04:03 'to _s' method takes number base as an argument.
04:08 The conversion depends on this number base.
04:12 Now, let us try out these methods.
04:15 Go to the terminal. Let's clear the terminal first.
04:21 Press Ctrl, L to clear the irb console.
04:25 Now, type: y equal to 20 and press Enter.
04:32 Here, we have declared a variable called 'y' and assigned a value 20 to it.
04:39 We will now convert 'y' to a floating point value using to underscore f method.
04:47 Type: y dot to underscore f and press Enter.
04:55 We get the value as float.
04:57 Now, type: y dot to underscore s and press Enter.
05:06 We get the output as 20, within double quotes.
05:10 To convert variable 'y' in binary form, give number base as 2 in the to_s method.
05:18 Press the up-arrow key to get the previous command.
05:22 Type: opening bracket 2 closing bracket and press Enter.
05:29 We get the output in the binary form.
05:33 Similarly, you can convert variable 'y' to octal or hexadecimal form
05:39 by changing the number base to 8 or 16.
05:44 Let us switch back to our slide.
05:47 We will now learn what is a variable scope.
05:51 Scope defines- where in a program, a variable is accessible.
05:56 Ruby has four types of variable scopes:
06:00 Local, Global
06:02 Instance and
06:04 Class.
06:06 Each variable type is declared by using a special character at the beginning of the variable name.
06:14 '$' represents global variable.
06:18 Lower case letters and underscore represent a local variable.
06:25 '@' represents an instance variable.
06:29 Two '@@' symbols represent a class variable.
06:33 Upper case letters represent a constant.
06:37 We will learn in detail, about this, in another tutorial.
06:42 This brings us to the end of this Spoken Tutorial. Let us summarize.
06:48 In this tutorial, we have learnt:
06:51 To declare a variable, e.g. var1=10
06:56 Changing a variable type using 'to_f' and 'to_s' methods
07:04 Different variable scopes.
07:06 As an assignment,
07:08 declare a variable and convert it to octal and hexadecimal form.
07:14 Watch the video available at the following link.
07:17 It summarizes the Spoken Tutorial project.
07:20 If you do not have good bandwidth, you can download and watch it.
07:24 The Spoken Tutorial project team :
07:27 Conducts workshops using spoken tutorials.
07:30 Gives certificates to those who pass an online test.
07:34 For more details, please write to: contact @ spoken hyphen tutorial dot org.
07:41 Spoken Tutorial project is a part of the Talk to a Teacher project.
07:45 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
07:51 More information on this mission is available at the below link.
07:57 This is Afrin Pinjari from IIT Bombay, signing off. Thank you for watching.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha

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