Difference between revisions of "Ruby/C2/Logical-and-other-Operators/English-timed"

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{| border=1
 
{| border=1
−
|| ''Time'''
+
|| '''Time'''
 
|| '''Narration'''
 
|| '''Narration'''
  
 
|-
 
|-
−
|  00.02
+
|  00:02
−
| Welcome to this spoken tutorial on '''Logical & Other Operators. '''
+
| Welcome to this '''Spoken Tutorial''' on '''Logical & Other Operators. '''
  
 
|-
 
|-
−
| 00.06
+
| 00:06
−
| In this tutorial we will learn  
+
| In this tutorial, we will learn:
  
 
|-
 
|-
−
| 00.09
+
| 00:09
 
| '''Logical Operators '''
 
| '''Logical Operators '''
  
 
|-
 
|-
−
| 00.11
+
| 00:11
 
|'''Parallel assignment''' and  
 
|'''Parallel assignment''' and  
  
 
|-
 
|-
−
| 00.13
+
| 00:13
−
| '''Range Operators '''
+
| '''Range Operators '''.
  
 
|-
 
|-
−
|  00.15
+
|  00:15
−
|Here we are using  
+
|Here, we are using:
  
 
|-
 
|-
−
|  00.17
+
|  00:17
−
| '''Ubuntu Linux''' version 12.04  
+
| '''Ubuntu Linux''' version '''12.04'''
  
 
|-
 
|-
−
|  00.20
+
|  00:20
−
| ''' Ruby 1.9.3  '''
+
| ''' Ruby 1.9.3  '''
  
 
|-
 
|-
−
| 00.23
+
| 00:23
−
|To follow this tutorial you must know how to use ''' Terminal''' and '''Text editor''' in ''' Linux'''.  
+
|To follow this tutorial, you must know how to use ''' Terminal''' and '''Text editor''' in '''Linux'''.  
  
 
|-
 
|-
−
| 00.29
+
| 00:29
−
|You must also be familiar with '''irb'''  
+
|You must also be familiar with ''''irb''''.
 
    
 
    
−
 
 
|-
 
|-
−
|  00.33
+
|  00:33
−
| If not, for relevant tutorials, please visit our website  
+
| If not, for relevant tutorials, please visit our website.
−
 
+
−
 
+
  
 
|-
 
|-
−
| 00.38
+
| 00:38
−
|Logical Operators are also known as ''' Boolean Operators'''
+
|'''Logical operators''' are also known as ''' Boolean operators'''
  
 
|-
 
|-
−
|  00.42
+
|  00:42
 
|  because they evaluate parts of an expression  
 
|  because they evaluate parts of an expression  
  
 
|-
 
|-
−
| 00.45
+
| 00:45
 
|and return a ''' true''' or ''' false''' value.  
 
|and return a ''' true''' or ''' false''' value.  
  
 
|-
 
|-
−
| 00.48
+
| 00:48
−
|'''Logical Operators''' are,
+
|'''Logical Operators''' are-
  
 
|-
 
|-
−
| 00.51
+
| 00:51
−
| ''' double ampersand (&&)'''  that is '''(and)'''  
+
| double ampersand (&&) that is '''and'''  
  
 
|-
 
|-
−
| 00.54
+
| 00:54
−
| ''' double pipe (|| )'''  that is '''(or)'''  
+
| double '''pipe'''  that is '''or'''  
  
 
|-
 
|-
−
| 00.56
+
| 00:56
−
| ''' Exclamation (!)'''  that is '''(not)'''  
+
| Exclamation mark (!) that is '''not'''.
  
 
|-
 
|-
−
|  01.00
+
|  01:00
−
| '''&&(double ampersand)''' and '''and''' evaluate to '''true''' only if both the expressions are '''true.'''  
+
| '&&' (double ampersand) and '''and''' evaluate to '''true''' only if both the expressions are '''true.'''  
  
 
|-
 
|-
−
| 01.07
+
| 01:07
−
|Second expression is evaluated only if the first is '''true. '''  
+
|Second expression is evaluated only if the first is '''true.'''  
  
 
|-
 
|-
−
| 01.12
+
| 01:12
−
| Difference in the two forms is, precedence
+
| Difference in the two forms is precedence.
  
 
|-
 
|-
−
| 01.15
+
| 01:15
 
|Symbolic '''and'''  that is'''&&(double ampersand)''' has higher precedence.  
 
|Symbolic '''and'''  that is'''&&(double ampersand)''' has higher precedence.  
  
 
|-
 
|-
−
| 01.20
+
| 01:20
−
|Let's us see some examples now.  
+
|Let's see some examples now.  
  
 
|-
 
|-
−
| 01.22
+
| 01:22
 
|We will use '''irb''' for this.  
 
|We will use '''irb''' for this.  
−
 
  
 
|-
 
|-
−
|  01.25
+
|  01:25
−
|  Open the ''' terminal''' by pressing '''Ctrl, Alt and T''' keys simultaneously.  
+
|  Open the ''' terminal''' by pressing '''Ctrl, Alt''' and '''T''' keys simultaneously.  
  
 
|-
 
|-
−
|  01.31
+
|  01:31
−
|Type '''irb''' and press '''Enter''' to launch '''interactive Ruby'''
+
|Type "irb" and press '''Enter''' to launch '''interactive Ruby'''.
  
 
|-
 
|-
−
|  01.36
+
|  01:36
−
| Type ''' 3 greater than 2 space double ampersand space 4 less than 5'''  
+
| Type: ''' 3 greater than 2 space double ampersand space 4 less than 5'''.
−
 
+
  
 
|-
 
|-
−
| 01.47
+
| 01:47
−
| Press ''' Enter'''
+
| Press ''' Enter'''.
  
 
|-
 
|-
−
|  01.49
+
|  01:49
−
| We get the output as '''true.'''
+
| We get the output as "true".
  
 
|-
 
|-
−
| 01.53
+
| 01:53
−
|Here, '''expression1'''  that is 3>2 is '''true'''.  
+
|Here, expression1 that is 3>2 is '''true'''.  
  
 
|-
 
|-
−
| 01.59
+
| 01:59
−
|'''Expression 2''' that is 4<5 is also '''true.'''  
+
|Expression 2 that is 4<5 is also '''true.'''  
  
 
|-
 
|-
−
| 02.03
+
|02:03
−
| Since both the expressions are '''true''', we get output as '''true.'''  
+
|Since both the expressions are '''true''', we get output as '''true.'''  
−
 
+
  
 
|-
 
|-
−
| 02.08
+
| 02:08
−
|Now press '''Up Arrow''' key to get the previous command.  
+
|Now, press '''Up-Arrow''' key to get the previous command.  
  
 
|-
 
|-
−
| 02.12
+
|02:12
−
| And ''' replace the double ampersand''' symbol with the word ''' and.'''
+
| And replace the double ampersand symbol with the word "and".  
  
 
|-
 
|-
−
| 02.17
+
| 02:17
−
|  Press '''Enter '''
+
|  Press '''Enter'''.
  
 
|-
 
|-
−
|  02.19
+
|  02:19
 
|We get the same result.   
 
|We get the same result.   
  
 
|-
 
|-
−
|  02.22
+
|  02:22
−
| Now press up arrow key again to get the previous command.  
+
| Now, press up-arrow key again to get the previous command.  
  
 
|-
 
|-
−
|  02.27
+
|  02:27
−
| In ''' expression 1''' replace '''greater than''' sign with '''less than'''
+
| In expression1, replace greater-than sign with less-than,
−
 
+
  
 
|-
 
|-
−
| 02.32
+
| 02:32
−
|Press ''' Enter '''
+
|press ''' Enter '''
  
 
|-
 
|-
−
|  02.35
+
|  02:35
−
| We get the output as '''false.'''
+
| We get the output as "false".
  
 
|-
 
|-
−
| 02.38
+
| 02:38
−
|This is because ''' 3<2''' is '''false.'''
+
|This is because 3 < 2 is '''false.'''
  
 
|-
 
|-
−
|  02.43
+
|  02:43
 
| Since the first expression is '''false''', the second expression will not be evaluated.   
 
| Since the first expression is '''false''', the second expression will not be evaluated.   
  
 
|-
 
|-
−
| 02.49
+
| 02:49
−
| So, we get output as '''false.'''
+
| So, we get the output as "false".  
  
 
|-
 
|-
−
| 02.53
+
| 02:53
−
| ''' || (double pipe)''' and '''or''' evaluate to '''true''', if either '''expression''' is '''true.'''  
+
| double '''pipe''' and '''or''' evaluate to '''true''', if either '''expression''' is '''true.'''  
  
 
|-
 
|-
−
| 02.59
+
| 02:59
 
|Second expression is evaluated only if first is '''false.'''  
 
|Second expression is evaluated only if first is '''false.'''  
−
 
  
 
|-
 
|-
−
| 03.04
+
| 03:04
 
|Difference in the two forms is '''precedence.'''  
 
|Difference in the two forms is '''precedence.'''  
  
 
|-
 
|-
−
| 03.07
+
| 03:07
−
| Symbolic '''or''' i.e ''' "||" (double pipe) ''' has higher '''precedence.'''  
+
|Symbolic '''or''' i.e '''double pipe''' has higher '''precedence.'''  
  
 
|-
 
|-
−
|  03.11
+
|  03:11
 
|  Now, let's try some examples.   
 
|  Now, let's try some examples.   
  
 
|-
 
|-
−
| 03.15
+
| 03:15
−
|''' 10 greater than 6 space double pipe space 12 less than 7'''
+
|Type: '''10 greater than 6 space double pipe space 12 less than 7'''
  
 
|-
 
|-
−
| 03.23
+
| 03:23
 
| Press  '''Enter.'''  
 
| Press  '''Enter.'''  
  
 
|-
 
|-
−
| 03.26
+
| 03:26
−
|We get output as '''true.'''
+
|We get output as "true".
  
 
|-
 
|-
−
| 03.29
+
| 03:29
−
|Here '''expression 1''' that is '''10<6''' is '''true'''.
+
|Here expression 1, that is '''10>6''', is '''true'''.
  
 
|-
 
|-
−
| 03.35
+
| 03:35
−
| Since the first expression is '''true''' , second expression will not be evaluated.  
+
| Since the first expression is '''true''', second expression will not be evaluated.  
  
 
|-
 
|-
−
| 03.40
+
| 03:40
 
|So, we get the output as '''true. '''
 
|So, we get the output as '''true. '''
−
 
  
 
|-
 
|-
−
|  03.42
+
|  03:42
−
|  Now press the '''Up Arrow''' key to get the previous command.  
+
|  Now, press the '''Up-Arrow''' key to get the previous command.  
  
 
|-
 
|-
−
|  03.46
+
|  03:46
−
|  In '''expression 1''' replace '''greater than sign''' with '''less than sign.'''
+
|  In '''expression 1''' replace '''greater than''' sign with '''less than''' sign
  
 
|-
 
|-
−
|  03.52
+
|  03:52
−
|  And replace '''pipe''' symbol with the word '''or.'''  
+
|  and replace '''pipe''' symbol with the word '''or.'''  
  
 
|-
 
|-
−
|  03.57
+
|  03:57
 
|  Press '''Enter.'''  
 
|  Press '''Enter.'''  
  
 
|-
 
|-
−
| 04.00
+
| 04:00
 
|Here, '''expression1''' that is 10<6 is '''false. '''
 
|Here, '''expression1''' that is 10<6 is '''false. '''
  
 
|-
 
|-
−
|  04.05
+
|  04:05
 
| '''Expression 2''' that is 12<7 is also '''false. '''
 
| '''Expression 2''' that is 12<7 is also '''false. '''
  
 
|-
 
|-
−
|  04.10
+
|  04:10
−
|  Since both the expressions are '''false''', we get output as '''false. '''
+
|  Since both the expressions are '''false''', we get output as "false".  
  
 
|-
 
|-
−
| 04.15
+
| 04:15
−
|'''! (exclamation mark )''' and '''not''' operators return the opposite value of the expression  
+
|'!' (exclamation mark ) and '''not''' operators return the opposite value of the expression.
  
 
|-
 
|-
−
|  04.20
+
|  04:20
−
|  If the '''expression''' is '''true''', '''exclamation mark'''  operator will return a '''false''' value.  
+
|  If the expression is '''true''', exclamation mark operator will return a '''false''' value.  
  
 
|-
 
|-
−
| 04.27
+
| 04:27
 
|It will return '''true''' if the expression is '''false'''.  
 
|It will return '''true''' if the expression is '''false'''.  
  
 
|-
 
|-
−
|  04.30
+
|  04:30
−
| Difference in the two forms is '''precedence. '''
+
| Difference in the two forms is '''precedence.'''
  
 
|-
 
|-
−
| 04.33
+
| 04:33
−
| Symbolic '''not that is (!)''' has higher '''precedence.'''  
+
| Symbolic '''not''', that is '!', has higher '''precedence.'''  
  
 
|-
 
|-
−
|  04.37
+
|  04:37
−
| Let's try out the '''not''' operator.  
+
| Let's try out the "not" operator.  
  
 
|-
 
|-
−
| 04.40
+
| 04:40
−
|First type ''' 10 double equal to 10'''
+
|First, type: '''10 double equal to 10'''
  
 
|-
 
|-
−
|  04.45
+
|  04:45
−
|  Press '''Enter '''
+
|  Press '''Enter '''.
  
 
|-
 
|-
−
| 04.47
+
| 04:47
−
|We get the output as '''true.'''
+
|We get the output as "true".
  
 
|-
 
|-
−
| 04.50
+
| 04:50
−
|To invert the result of above expression,  
+
|To '''invert''' the result of above expression,  
  
 
|-
 
|-
−
|  04.53
+
|  04:53
−
| let's add the '''not''' operator before the expression.  
+
| let's add the "not" operator before the expression.  
−
 
+
  
 
|-
 
|-
−
| 04.57
+
| 04:57
−
|Type '''Exclamation mark within brackets 10 double equal to 10 '''
+
|Type: exclamation mark within brackets '''10 double equal to 10 '''.
−
 
+
  
 
|-
 
|-
−
|  05.04
+
|  05:04
 
| Press '''Enter. '''
 
| Press '''Enter. '''
−
 
  
 
|-
 
|-
−
|  05.06
+
|  05:06
−
|We get the output as '''false.'''
+
|We get the output as "false".
  
 
|-
 
|-
−
| 05.10
+
| 05:10
 
| Press '''Ctrl+L''' simultaneously to clear the '''irb''' console.  
 
| Press '''Ctrl+L''' simultaneously to clear the '''irb''' console.  
  
 
|-
 
|-
−
| 05.15
+
| 05:15
−
|Next, let us learn about '''parallel assignment. '''
+
|Next, let us learn about '''parallel assignment.'''
  
 
|-
 
|-
−
| 05.20
+
| 05:20
 
|Multiple variables can be initialized with a single line of '''Ruby''' code, through '''parallel assignment. '''
 
|Multiple variables can be initialized with a single line of '''Ruby''' code, through '''parallel assignment. '''
  
 
|-
 
|-
−
| 05.26
+
| 05:26
 
| Let's switch to the '''terminal.'''
 
| Let's switch to the '''terminal.'''
  
 
|-
 
|-
−
| 05.29
+
| 05:29
−
|Let's declare three variables '''a, b, c''' using '''parallel assignment. '''
+
|Let's declare three variables 'a', 'b', 'c' using '''parallel assignment. '''
  
 
|-
 
|-
−
| 05.36
+
| 05:36
−
| Type '''a comma b comma c equal to 10 comma 20 comma 30 '''
+
| Type: '''a comma b comma c equal to 10 comma 20 comma 30'''
  
 
|-
 
|-
−
| 05.45
+
| 05:45
 
| and press '''Enter. '''
 
| and press '''Enter. '''
  
 
|-
 
|-
−
| 05.47
+
| 05:47
−
|Here, '''10''' will be assigned to variable '''a '''
+
|Here, 10 will be assigned to variable 'a',
  
 
|-
 
|-
−
| 05.52
+
| 05:52
−
|'''20''' will be assigned to variable '''b '''
+
|20 will be assigned to variable 'b'
  
 
|-
 
|-
−
| 05.54
+
| 05:54
−
|'''30''' will be assigned to variable '''c '''
+
|30 will be assigned to variable 'c'.
−
 
+
  
 
|-
 
|-
−
| 05.56
+
| 05:56
−
|The right hand side acts as an '''array'''.  
+
|The right-hand side acts as an '''array'''.  
  
 
|-
 
|-
−
| 06.01
+
| 06:01
−
|If we list multiple variables on the left hand side,  then the array is unpacked and assigned into the respective variables.  
+
|If we list multiple variables on the left hand side then the array is unpacked and assigned into the respective variables.  
  
 
|-
 
|-
−
| 06.10
+
| 06:10
−
|We will learn about '''arrays''' in detail in the upcoming tutorials.  
+
|We will learn about '''arrays''' in detail, in the upcoming tutorials.  
  
 
|-
 
|-
−
| 06.14
+
| 06:14
−
| For now, let's check whether the '''assignment''' is done properly.  
+
| For now, let's check whether the assignment is done properly.  
  
 
|-
 
|-
−
|06.20
+
|06:20
−
| Type '''a''' and press '''Enter.'''
+
| Type 'a' and press '''Enter.'''
  
 
|-
 
|-
−
| 06.23
+
| 06:23
−
|Value '''10''' stored in variable '''a''' is displayed.  
+
|Value 10, stored in variable 'a', is displayed.  
  
 
|-
 
|-
−
| 06.28
+
| 06:28
−
|Type '''b''' and press '''Enter.'''
+
|Type 'b' and press '''Enter.'''
  
 
|-
 
|-
−
| 06.31
+
| 06:31
−
|We get 20  
+
|We get 20.
  
 
|-
 
|-
−
|  06.33
+
|  06:33
−
| Type '''c''' and press '''Enter.'''
+
| Type 'c' and press '''Enter.'''
  
 
|-
 
|-
−
| 06.37
+
| 06:37
−
|30 is displayed.  
+
| 30 is displayed.  
−
 
+
  
 
|-
 
|-
−
|  06.40
+
|  06:40
 
|  '''Parallel assignment''' is also useful for swapping the values stored in two variables.  
 
|  '''Parallel assignment''' is also useful for swapping the values stored in two variables.  
 +
 
|-
 
|-
−
| 06.45
+
| 06:45
−
|Let us swap the values of variables a and b.
+
|Let us swap the values of variables 'a' and 'b'.
  
 
|-
 
|-
−
| 06.50
+
| 06:50
−
|Type '''puts space within double quotes a equal to hash within curly brackets a comma within double quotes b equal to hash within curly brackets b'''  
+
|Type: '''puts space within double quotes a equal to hash within curly brackets a comma within double quotes b equal to hash within curly brackets b'''  
  
 
|-
 
|-
−
| 07.11
+
| 07:11
 
| Press '''Enter. '''
 
| Press '''Enter. '''
  
 
|-
 
|-
−
| 07.13
+
| 07:13
−
| We get the output as '''a=10 '''
+
| We get the output as '''a=10'''
  
 
|-
 
|-
−
| 07.16
+
| 07:16
−
|'''b=20 '''
+
|'''b=20.'''
  
 
|-
 
|-
−
| 07.20
+
| 07:20
−
|Now let's swap a and b.
+
|Now, let's swap 'a' and 'b'.
  
 
|-
 
|-
−
| 07.23
+
| 07:23
−
|To do so type  
+
|To do so, type:
  
 
|-
 
|-
−
| 07.25
+
| 07:25
 
|'''a comma b equal to b comma a '''
 
|'''a comma b equal to b comma a '''
  
 
|-
 
|-
−
| 07.31
+
| 07:31
 
|Press '''Enter.'''  
 
|Press '''Enter.'''  
  
 
|-
 
|-
−
| 07.33
+
| 07:33
−
| Press '''Up Arrow''' key twice to get the '''puts''' command and press '''Enter.'''
+
| Press '''Up-Arrow''' key twice to get the '''puts''' command and press '''Enter.'''
  
 
|-
 
|-
−
|  07.39
+
|  07:39
−
|  We get the output as  
+
|  We get the output as-
  
 
|-
 
|-
−
| 07.41
+
| 07:41
 
|'''a=20 '''
 
|'''a=20 '''
  
 
|-
 
|-
−
| 07.44
+
| 07:44
−
| '''b=10 '''
+
| '''b=10 '''.
−
 
+
  
 
|-
 
|-
−
| 07.47
+
| 07:47
 
| We will now learn about '''range''' in '''Ruby.'''
 
| We will now learn about '''range''' in '''Ruby.'''
  
 
|-
 
|-
−
| 07.50
+
| 07:50
−
|The values in a '''range''' can be numbers, characters, strings or objects.  
+
|The values in a '''range''' can be numbers, characters, '''string'''s or '''object'''s.  
  
 
|-
 
|-
−
| 07.58
+
| 07:58
 
|'''Ranges''' are used to express a '''sequence. '''
 
|'''Ranges''' are used to express a '''sequence. '''
  
 
|-
 
|-
−
| 08.02
+
| 08:02
 
|'''Sequence range''' is used to create a range of successive values.  
 
|'''Sequence range''' is used to create a range of successive values.  
  
 
|-
 
|-
−
| 08.06
+
| 08:06
 
|It consists of a start value, range of values and an end value.  
 
|It consists of a start value, range of values and an end value.  
  
 
|-
 
|-
−
| 08.13
+
| 08:13
 
|'''(..) two dot operator''' creates ''' inclusive range. '''
 
|'''(..) two dot operator''' creates ''' inclusive range. '''
  
 
|-
 
|-
−
| 08.16
+
| 08:16
 
|'''(...) three dot operator''' creates an '''exclusive range. '''
 
|'''(...) three dot operator''' creates an '''exclusive range. '''
  
 
|-
 
|-
−
| 08.20
+
| 08:20
−
|'''Ranges''' are used to identify whether a value falls within a particular range, too.  
+
|'''Ranges''' are used to identify whether a value falls within a particular range too.  
  
 
|-
 
|-
−
| 08.26
+
| 08:26
 
|We do this using (===) the '''equality''' operator.   
 
|We do this using (===) the '''equality''' operator.   
  
 
|-
 
|-
−
| 08.30
+
| 08:30
 
|Let us try out some examples on '''ranges.'''
 
|Let us try out some examples on '''ranges.'''
  
 
|-
 
|-
−
| 08.33
+
| 08:33
 
|Let's switch to '''terminal. '''
 
|Let's switch to '''terminal. '''
  
 
|-
 
|-
−
| 08.36
+
| 08:36
−
|Type '''Within brackets 1 two dots 10 then dot to underscore a '''
+
|Type: within brackets ''' 1 two dots 10''' then '''dot to underscore a'''  
−
 
+
  
 
|-
 
|-
−
| 08.46
+
| 08:46
 
|'''Two dot''' operator creates '''inclusive range. '''
 
|'''Two dot''' operator creates '''inclusive range. '''
  
 
|-
 
|-
−
| 08.50
+
| 08:50
−
|'''Inclusive operator''' includes both begin and end values in a range.  
+
|'''Inclusive operator''' includes both, begin and end values, in a range.  
  
 
|-
 
|-
−
| 08.57
+
| 08:57
−
|Here '''to_a''' method is used to convert a '''range''' to a list.  
+
|Here '''to_a''' '''method''' is used to convert a '''range''' to a list.  
  
 
|-
 
|-
−
| 09.03
+
| 09:03
 
|Press '''Enter. '''
 
|Press '''Enter. '''
  
 
|-
 
|-
−
| 09.05
+
| 09:05
−
|Here you can see the values 1 and 10 are included in the range.  
+
|Here, you can see the values 1 and 10 are included in the range.  
  
 
|-
 
|-
−
| 09.11
+
| 09:11
−
|Now we will see an '''exclusive range''' operator.  
+
|Now, we will see an '''exclusive range''' operator.  
  
 
|-
 
|-
−
| 09.16
+
| 09:16
−
|Type  '''Within brackets 1 three dots 10 then dot to underscore a '''
+
|Type: within brackets '''1 three dots 10''' then '''dot to underscore a'''.
  
 
|-
 
|-
−
| 09.27
+
| 09:27
 
|'''Three dot''' operator creates an '''exclusive range. '''
 
|'''Three dot''' operator creates an '''exclusive range. '''
  
 
|-
 
|-
−
| 09.31
+
| 09:31
 
|'''Exclusive range''' operator excludes the end value from the sequence.  
 
|'''Exclusive range''' operator excludes the end value from the sequence.  
  
 
|-
 
|-
−
| 09.37
+
| 09:37
 
|Press '''Enter. '''
 
|Press '''Enter. '''
  
 
|-
 
|-
−
| 09.39
+
| 09:39
−
|Here the end value 10 is not included in the range.  
+
|Here, the end value 10 is not included in the range.  
−
 
+
  
 
|-
 
|-
−
| 09.45
+
| 09:45
−
|Now let's check whether 5 lies in the range of 1 to 10.  
+
|Now, let's check whether 5 lies in the range of 1 to 10.  
  
 
|-
 
|-
−
| 09.50
+
| 09:50
−
|Type '''Within brackets 1 two dots 10 three times equal to and then 5 '''
+
|Type: within brackets '''1 two dots 10 three times equal to''' and then '''5'''.
−
 
+
  
 
|-
 
|-
−
| 10.00
+
| 10:00
 
|Press '''Enter. '''
 
|Press '''Enter. '''
  
 
|-
 
|-
−
| 10.02
+
| 10:02
−
|'''Equality operator''' is used to check whether a value lies in the range.  
+
|Equality operator is used to check whether a value lies in the range.  
  
 
|-
 
|-
−
| 10.07
+
| 10:07
−
|We get the output as '''true''' since 5 lies in the range 1 to 10.  
+
|We get the output as "true" since 5 lies in the range 1 to 10.  
  
 
|-
 
|-
−
| 10.14
+
| 10:14
 
|This brings us to the end of this Spoken Tutorial.  
 
|This brings us to the end of this Spoken Tutorial.  
  
 
|-
 
|-
−
| 10.17
+
| 10:17
−
|In this tutorial, we have learnt  
+
|In this tutorial, we have learnt:
−
 
+
  
 
|-
 
|-
−
| 10.20
+
| 10:20
−
| '''Logical operator''' i.e '''&&,||, !(double ampersand, double pipe and exclamation mark operators)'''
+
|'''Logical operator''' i.e double ampersand, double '''pipe''' and exclamation mark operators.
  
 
|-
 
|-
−
| 10.27
+
| 10:27
−
|'''Parallel assignment''' Ex: a,b,c=10,20,30  
+
|'''Parallel assignment''' Ex: a, b, c = 10, 20, 30  
  
 
|-
 
|-
−
| 10.34
+
| 10:34
−
|'''Range Operator Inclusive operator '''(..) and Exclusive operator(...)'''
+
|'''Range Operator- Inclusive operator '''(..) and '''Exclusive operator(...)'''.
  
 
|-
 
|-
−
| 10.39
+
| 10:39
−
|As an assignment  
+
|As an assignment,
  
 
|-
 
|-
−
| 10.41
+
| 10:41
−
|Declare two variables using '''parallel assignment''' and  
+
|declare two variables using '''parallel assignment''' and  
  
 
|-
 
|-
−
| 10.45
+
| 10:45
−
|Check whether their sum lies between 20 and 50  
+
|check whether their sum lies between 20 and 50.
−
 
+
  
 
|-
 
|-
−
|  10.49
+
|  10:49
 
|  Watch the video available at the following link.
 
|  Watch the video available at the following link.
  
 
|-
 
|-
−
| 10.52
+
| 10:52
−
|It summarises the Spoken Tutorial project.
+
|It summarizes the Spoken Tutorial project.
  
 
|-
 
|-
−
| 10.56
+
| 10:56
 
|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.  
  
 
|-
 
|-
−
|  11.00
+
|  11:00
−
| The Spoken Tutorial Project Team :
+
| The Spoken Tutorial project team:
  
 
|-   
 
|-   
−
| 11.03
+
| 11:03
−
|Conducts workshops using spoken tutorials  
+
|Conducts workshops using spoken tutorials.
  
 
|-
 
|-
−
|11.05
+
|11:05
−
|Gives certificates to those who pass an online test  
+
|Gives certificates to those who pass an online test.
  
 
|-
 
|-
−
| 11.09
+
| 11:09
−
|For more details, please write to contact@spoken-tutorial.org
+
|For more details, please write to:contact@spoken-tutorial.org
  
 
|-
 
|-
−
|  11.15
+
|  11:15
−
| 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.
  
 
|-
 
|-
−
| 11.19
+
| 11:19
 
|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.
  
 
|-
 
|-
−
| 11.25
+
| 11:25
−
|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: spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
  
 
|-
 
|-
−
| 11.34
+
| 11:34
−
|This script has been contributed by the spoken tutorial team IIT Bombay  
+
|This script has been contributed by the spoken tutorial team, '''IIT Bombay'''.
  
 
|-
 
|-
−
| 11.38
+
| 11:38
−
|And this is Shalini Nair signing off  Thank you  
+
|And this is Shalini Nair, signing off. Thank you.
−
 
+
  
 
|}
 
|}

Latest revision as of 15:14, 27 March 2017

Time Narration
00:02 Welcome to this Spoken Tutorial on Logical & Other Operators.
00:06 In this tutorial, we will learn:
00:09 Logical Operators
00:11 Parallel assignment and
00:13 Range Operators .
00:15 Here, we are using:
00:17 Ubuntu Linux version 12.04
00:20 Ruby 1.9.3
00:23 To follow this tutorial, you must know how to use Terminal and Text editor in Linux.
00:29 You must also be familiar with 'irb'.
00:33 If not, for relevant tutorials, please visit our website.
00:38 Logical operators are also known as Boolean operators
00:42 because they evaluate parts of an expression
00:45 and return a true or false value.
00:48 Logical Operators are-
00:51 double ampersand (&&) that is and
00:54 double pipe that is or
00:56 Exclamation mark (!) that is not.
01:00 '&&' (double ampersand) and and evaluate to true only if both the expressions are true.
01:07 Second expression is evaluated only if the first is true.
01:12 Difference in the two forms is precedence.
01:15 Symbolic and that is&&(double ampersand) has higher precedence.
01:20 Let's see some examples now.
01:22 We will use irb for this.
01:25 Open the terminal by pressing Ctrl, Alt and T keys simultaneously.
01:31 Type "irb" and press Enter to launch interactive Ruby.
01:36 Type: 3 greater than 2 space double ampersand space 4 less than 5.
01:47 Press Enter.
01:49 We get the output as "true".
01:53 Here, expression1 that is 3>2 is true.
01:59 Expression 2 that is 4<5 is also true.
02:03 Since both the expressions are true, we get output as true.
02:08 Now, press Up-Arrow key to get the previous command.
02:12 And replace the double ampersand symbol with the word "and".
02:17 Press Enter.
02:19 We get the same result.
02:22 Now, press up-arrow key again to get the previous command.
02:27 In expression1, replace greater-than sign with less-than,
02:32 press Enter
02:35 We get the output as "false".
02:38 This is because 3 < 2 is false.
02:43 Since the first expression is false, the second expression will not be evaluated.
02:49 So, we get the output as "false".
02:53 double pipe and or evaluate to true, if either expression is true.
02:59 Second expression is evaluated only if first is false.
03:04 Difference in the two forms is precedence.
03:07 Symbolic or i.e double pipe has higher precedence.
03:11 Now, let's try some examples.
03:15 Type: 10 greater than 6 space double pipe space 12 less than 7
03:23 Press Enter.
03:26 We get output as "true".
03:29 Here expression 1, that is 10>6, is true.
03:35 Since the first expression is true, second expression will not be evaluated.
03:40 So, we get the output as true.
03:42 Now, press the Up-Arrow key to get the previous command.
03:46 In expression 1 replace greater than sign with less than sign
03:52 and replace pipe symbol with the word or.
03:57 Press Enter.
04:00 Here, expression1 that is 10<6 is false.
04:05 Expression 2 that is 12<7 is also false.
04:10 Since both the expressions are false, we get output as "false".
04:15 '!' (exclamation mark ) and not operators return the opposite value of the expression.
04:20 If the expression is true, exclamation mark operator will return a false value.
04:27 It will return true if the expression is false.
04:30 Difference in the two forms is precedence.
04:33 Symbolic not, that is '!', has higher precedence.
04:37 Let's try out the "not" operator.
04:40 First, type: 10 double equal to 10
04:45 Press Enter .
04:47 We get the output as "true".
04:50 To invert the result of above expression,
04:53 let's add the "not" operator before the expression.
04:57 Type: exclamation mark within brackets 10 double equal to 10 .
05:04 Press Enter.
05:06 We get the output as "false".
05:10 Press Ctrl+L simultaneously to clear the irb console.
05:15 Next, let us learn about parallel assignment.
05:20 Multiple variables can be initialized with a single line of Ruby code, through parallel assignment.
05:26 Let's switch to the terminal.
05:29 Let's declare three variables 'a', 'b', 'c' using parallel assignment.
05:36 Type: a comma b comma c equal to 10 comma 20 comma 30
05:45 and press Enter.
05:47 Here, 10 will be assigned to variable 'a',
05:52 20 will be assigned to variable 'b'
05:54 30 will be assigned to variable 'c'.
05:56 The right-hand side acts as an array.
06:01 If we list multiple variables on the left hand side then the array is unpacked and assigned into the respective variables.
06:10 We will learn about arrays in detail, in the upcoming tutorials.
06:14 For now, let's check whether the assignment is done properly.
06:20 Type 'a' and press Enter.
06:23 Value 10, stored in variable 'a', is displayed.
06:28 Type 'b' and press Enter.
06:31 We get 20.
06:33 Type 'c' and press Enter.
06:37 30 is displayed.
06:40 Parallel assignment is also useful for swapping the values stored in two variables.
06:45 Let us swap the values of variables 'a' and 'b'.
06:50 Type: puts space within double quotes a equal to hash within curly brackets a comma within double quotes b equal to hash within curly brackets b
07:11 Press Enter.
07:13 We get the output as a=10
07:16 b=20.
07:20 Now, let's swap 'a' and 'b'.
07:23 To do so, type:
07:25 a comma b equal to b comma a
07:31 Press Enter.
07:33 Press Up-Arrow key twice to get the puts command and press Enter.
07:39 We get the output as-
07:41 a=20
07:44 b=10 .
07:47 We will now learn about range in Ruby.
07:50 The values in a range can be numbers, characters, strings or objects.
07:58 Ranges are used to express a sequence.
08:02 Sequence range is used to create a range of successive values.
08:06 It consists of a start value, range of values and an end value.
08:13 (..) two dot operator creates inclusive range.
08:16 (...) three dot operator creates an exclusive range.
08:20 Ranges are used to identify whether a value falls within a particular range too.
08:26 We do this using (===) the equality operator.
08:30 Let us try out some examples on ranges.
08:33 Let's switch to terminal.
08:36 Type: within brackets 1 two dots 10 then dot to underscore a
08:46 Two dot operator creates inclusive range.
08:50 Inclusive operator includes both, begin and end values, in a range.
08:57 Here to_a method is used to convert a range to a list.
09:03 Press Enter.
09:05 Here, you can see the values 1 and 10 are included in the range.
09:11 Now, we will see an exclusive range operator.
09:16 Type: within brackets 1 three dots 10 then dot to underscore a.
09:27 Three dot operator creates an exclusive range.
09:31 Exclusive range operator excludes the end value from the sequence.
09:37 Press Enter.
09:39 Here, the end value 10 is not included in the range.
09:45 Now, let's check whether 5 lies in the range of 1 to 10.
09:50 Type: within brackets 1 two dots 10 three times equal to and then 5.
10:00 Press Enter.
10:02 Equality operator is used to check whether a value lies in the range.
10:07 We get the output as "true" since 5 lies in the range 1 to 10.
10:14 This brings us to the end of this Spoken Tutorial.
10:17 In this tutorial, we have learnt:
10:20 Logical operator i.e double ampersand, double pipe and exclamation mark operators.
10:27 Parallel assignment Ex: a, b, c = 10, 20, 30
10:34 Range Operator- Inclusive operator (..) and Exclusive operator(...).
10:39 As an assignment,
10:41 declare two variables using parallel assignment and
10:45 check whether their sum lies between 20 and 50.
10:49 Watch the video available at the following link.
10:52 It summarizes the Spoken Tutorial project.
10:56 If you do not have good bandwidth, you can download and watch it.
11:00 The Spoken Tutorial project team:
11:03 Conducts workshops using spoken tutorials.
11:05 Gives certificates to those who pass an online test.
11:09 For more details, please write to:contact@spoken-tutorial.org
11:15 Spoken Tutorial project is a part of the Talk to a Teacher project.
11:19 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
11:25 More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
11:34 This script has been contributed by the spoken tutorial team, IIT Bombay.
11:38 And this is Shalini Nair, signing off. Thank you.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Ranjana, Sandhya.np14

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