Ruby/C2/Logical-and-other-Operators/English - Revision history

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Sanmugam at 16:29, 11 April 2013

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Nancyvarkey: Created page with ''''Title of script''':''' Logical & Other Operators ''' '''Author:Spoken Tutorial Team, IIT Bombay''' '''Keywords:logical operator, range operator, video tutorial''' {| borde…'

2013-04-09T17:30:53Z

Created page with ''''Title of script''':''' Logical & Other Operators ''' '''Author:Spoken Tutorial Team, IIT Bombay''' '''Keywords:logical operator, range operator, video tutorial''' {| borde…'

New page

'''Title of script''':''' Logical & Other Operators '''

'''Author:Spoken Tutorial Team, IIT Bombay'''

'''Keywords:logical operator, range operator, video tutorial'''

{| border=1
| '''Visual Cue'''
| '''Narration'''

|-
| Slide 1
| Welcome to this spoken tutorial on Logical & Other Operators

|-
| Slide 2

Learning Objectives
| In this tutorial, we will learn

* Logical Operators
* Parallel assignment
* Range Operators

|-
| Slide 3

System Requirement
| Here we are using

* '''Ubuntu Linux '''version 12.04
* '''Ruby''' 1.9.3

|-
| Slide 4

Pre-requisites
| To follow this tutorial you must know how to use''' Terminal''' and Text editor in '''Linux.'''

You must also be familiar with '''irb'''

If not, for relevant tutorials, please visit our website

|-
| Slide 5

Logical Operators
| Logical Operators are also known as '''Boolean Operators''' .

Because they evaluate parts of an expression and return a '''true''' or ''false''' value.

Logical Operators are,

* '''&& (and)'''
* '''|| (or)'''
* '''! (not)'''

|-
| Slide 6

Logical operators

| '''&&''' and '''and'''

<nowiki>Eg : <Expresion1> </nowiki>'''&&'''<nowiki><Expression2></nowiki>

<nowiki><Expresion1> </nowiki>'''and'''<nowiki><Expression2></nowiki>

|-
| Highlight''' “&&” '''and''' “and”'''
| '''and''' and '''&&''' evaluate to '''true '''only if both the expressions are '''true'''.

Second expression is evaluated only if the first is '''true'''.

|-
| Highlight''' “&&”'''
| Difference in the two forms is, '''precedence'''

Symbolic '''and (&&) '''has higher '''precedence'''.

|-
| Slide 7

| '''<nowiki>||</nowiki>''' and '''or'''

<nowiki>Eg : <Expresion1></nowiki> '''||''' <nowiki><Expression2></nowiki>

<nowiki><Expresion1></nowiki> '''or''' <nowiki><Expression2></nowiki>

|-
|Highlight '''<nowiki>||</nowiki>''' and '''or'''
|'''<nowiki>||</nowiki>''' and '''or''' evaluate to '''true''', if either '''operand''' is '''true'''.

Second expression is evaluated only if first is '''false'''.
|-
| Highlight '''<nowiki>||</nowiki>'''
| Difference in the two forms is '''precedence'''.

Symbolic '''or''' ('''<nowiki>"||"</nowiki>''') has higher '''precedence'''.

|-
| Slide 8

| '''<nowiki>!</nowiki>''' and '''not'''

Eg: '''<nowiki>!</nowiki>'''<Expression>

'''not'''<Expression>

|-
| Highlight '''<nowiki>!</nowiki>''' and '''not'''
| '''not''' and '''<nowiki>!</nowiki>''' return the opposite value of the expression

If the expression is '''true''', '''<nowiki>!</nowiki>''' operator will return a '''false''' value.

It will return '''true''' if the expression is '''false'''.

|-
| Highlight '''<nowiki>!</nowiki>'''
| Difference in the two forms is '''precedence'''.

Symbolic '''not <nowiki>(!)</nowiki>''' has higher '''precedence'''.

|-
|
| Lets us see some examples now.

We will use '''irb '''for this.

|-
| Press '''Ctrl+Alt+t '''to switch to the '''terminal'''
| Open the '''terminal''' by pressing '''Ctrl, Alt''' and '''T '''keys simultaneously.

|-
| Type

'''irb''' and press '''Enter'''
| Type''' irb '''and press '''Enter '''to launch '''interactive Ruby'''

|-
| Type

'''3>2 && 4<5'''

Press '''Enter'''
| Type

'''3 greater than 2 space ampersand ampersand space 4 less than 5'''

Press''' Enter'''

|-
| Highlight '''true'''
| We get the output as '''true.'''

|-
| Highlight '''3>2'''

Highlight '''<nowiki>4<5</nowiki>'''
| Here, '''expression1''' that is '''3>2 '''is '''true'''.

'''Expression 2 '''that is '''<nowiki>4<5 </nowiki>'''is also '''true.'''

Since both the expressions are '''true''', we get output as '''true.'''

|-
| Press the up Arrow key
| Now press '''Up''' '''Arrow''' key to get the previous command.

|-
| Replace

'''<nowiki>3<2 and 4<5</nowiki>'''

press '''Enter'''
| In '''expression 1 '''replace '''greater than''' sign with '''less than'''

And replace the double '''ampersand '''symbol''' '''with the word '''and.'''

Press''' Enter'''

|-
| Highlight '''false'''
| We get the output as '''false.'''

|-
| Highlight '''<nowiki>3<2</nowiki>'''
| Here '''expression 1''' that is '''<nowiki>3<2 </nowiki>'''is '''false.'''

Since the first expression is '''false''', the second expression will not be evaluated.

So, we get output as '''false'''.

|-
|
| Now, let's try the '''or''' operator.

|-
| Type

'''<nowiki>10>6 || 12 <7</nowiki>'''
| '''10 greater than 6 space double pipe space 12 less than 7'''

Press '''Enter.'''

|-
| Highlight '''true'''
| We get output as '''true.'''

|-
| Highlight '''<nowiki>10<6</nowiki>'''
| Here '''expression 1''' that is '''<nowiki>10<6 </nowiki>'''is '''true.'''

Since the first expression is''' true ''', second expression will not be evaluated.

So, we get the output as '''true'''.

|-
| Press the up Arrow key
| Now press the '''Up Arrow '''key to get the previous command.

|-
| Replace

'''<nowiki>10<6 </nowiki>or<nowiki> 12<7</nowiki>'''

press '''Enter'''
| In '''expression 1 '''replace '''greater than''' sign with '''less than.'''

And replace '''pipe '''symbol with word '''or.'''

Press '''Enter.'''

|-
| Highlight '''<nowiki>10<6</nowiki>'''

Highlight '''<nowiki>12<7</nowiki>'''
| Here, '''expression1''' that is '''<nowiki>10<6 </nowiki>'''is '''false'''.

'''Expression 2 '''that is '''<nowiki>12<7 </nowiki>'''is also '''false'''.

Since both the expressions are '''false,''' we get output as '''false'''.

|-
|
| Let's try out the '''not '''operator.

|-
| Type

'''10==10'''

press Enter
| First type

'''10 double equal to 10'''

Press''' Enter.'''

|-
| Highlight '''true'''
| We get the output as '''true.'''

|-
|
| To invert the result of above expression,

let's add the '''not '''operator before the expression.

|-
| Type

'''!(10==10)'''

press '''Enter'''
| Type

'''Exclamation mark within brackets 10 double equal to 10'''

Press''' Enter.'''

|-
| Highlight''' false'''
| We get the output as '''false.'''

|-
| Press''' ctrl +l'''
| Press '''Ctrl+l '''simultaneously to clear the''' irb''' console.

|-
|
| <nowiki><Pause></nowiki>

Next, let us learn about '''parallel assignment.'''

|-
|
| Multiple variables can be initialized with a single line of '''Ruby''' code, through '''parallel assignment'''.

|-
|
| Lets us try this out using '''irb.'''

Go to the '''terminal.'''

|-
|
| Let's declare three variables '''a, b, c''' using '''parallel assignment. '''

|-
| Type

'''a,b,c =10,20,30'''

| Type

'''a comma b comma c equal to 10 comma 20 comma 30'''

and press '''Enter.'''

|-
| Highlight '''a,b,c =10,20,30'''

press '''Enter'''
| Here ,

'''10''' will be assigned to variable '''a'''

'''20''' will be assigned to variable '''b'''

'''30''' will be assigned to variable '''c'''

Press '''Enter.'''

|-
| Highlight '''10,20,30'''
| The right hand side acts as an '''array.'''

|-
| Highlight '''a,b,c'''<nowiki>=10,20,30</nowiki>
| If we list multiple variables on the left hand side,

then the array is unpacked and assigned into the respective variables.

|-
|
| We will learn about '''arrays '''in detail in the upcoming tutorials.

Now, let's check whether the '''assignment''' is done properly.

|-
| Type '''a'''<nowiki> << press Enter</nowiki>
| Type '''a''' and press '''Enter.'''

|-
| Highlight '''10 '''
| Value '''10''' stored in variable '''a '''is displayed.

|-
| Type '''b'''<nowiki><< press Enter</nowiki>
| Type '''b''' and press '''Enter.'''

|-
| Highlight 2'''0 '''
| Value 2'''0''' stored in variable '''b''' is displayed.

|-
| Type '''c '''<nowiki><< press Enter</nowiki>
| Type '''c''' and press '''Enter.'''

|-
| Highlight '''30 '''
| Value '''30''' stored in variable '''c '''is displayed.

|-
|
| '''Parallel assignment''' is also useful for swapping the values stored in two variables.

|-
|
| Let us swap the values of variables '''a''' and '''b.'''

|-
|
| First, let's us see what are the values of variables '''a''' and '''b '''before swapping.

|-
| Type '''puts “a=#{a}”,”b=#{b}”'''

press Enter
| 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 '''

Press '''Enter.'''

|-
| Highlight''' a=10'''

'''b=20'''
| We get the output as

'''a=10'''

'''b=20'''

|-
|
| Lets swap '''a''' and '''b.'''

|-
| Type

'''a,b=b,a'''
| To do so type

'''a comma b equal to b comma a'''

Press '''Enter.'''

|-
| Press Up Arrow key twice
| Press '''Up Arrow '''key twice to get the '''puts''' command and press''' Enter.'''

|-
| Highlight''' a=20'''

'''b=10'''
| We get the output as

'''a=20'''

'''b=10'''

|-
| Slide

'''Range'''
| We will now learn about '''range''' in '''Ruby.'''

The values in a '''range''' can be numbers, characters, strings or objects.

'''Ranges''' are used to express a '''sequence'''.

|-
| Sequence Range
| '''Sequence range''' is used to create a range of successive values.

It consists of an start value, range of values and an end value.

'''(..) '''two dot operator creates an '''inclusive range.'''

'''(...) '''three dot operator creates an '''exclusive range.'''

|-
| Range Interval
| Ranges are used to identify whether a value falls within a particular range, too.

We do this using''' (==<nowiki>=</nowiki>) '''the '''equality''' operator.

|-
|
| Let us try out some examples on '''ranges.'''

Let's switch to '''terminal.'''

Let's create a range between '''1''' to '''10.'''

|-
| Type '''(1..10).to_a'''
| Type

'''Within brackets 1 two dots 10 then dot to underscore a'''

|-
| Highlight '''(1..10).to _a'''
| '''Two dot''' operator creates '''inclusive range. '''

'''Inclusive operator''' includes both begin and end values in a range.

Here '''to_a '''method is used to convert a '''range''' to a list.

Press '''Enter.'''

|-
| Highlight'''<nowiki> [1 ,2, 3, 4, 5, 6, 7, 8, 9, 10] </nowiki>'''
| Here you can see the values '''1''' and '''10''' are included in the range.

|-
|
| Now we will see the '''exclusive range''' operator.

|-
| Type '''(1...10).to_a'''
| Type

'''Within brackets 1 three dots 10 then dot to underscore a'''

|-
| Highlight '''(1...10).to _a'''
| '''Three dot '''operator creates an '''exclusive range. '''

'''Exclusive range''' operator excludes the end value from the sequence.

Press''' Enter.'''

|-
| Highlight '''<nowiki>[1 ,2, 3, 4, 5, 6, 7, 8, 9]</nowiki>'''
| Here end value '''10''' is not included in the range.

|-
|
| Now lets check whether '''5''' lies in the range of '''1''' to '''10'''.

|-
| Type

'''(1..10)===5'''

| Type

'''Within brackets 1 two dots 10 three times equal to and then 5'''

Press '''Enter.'''

|-
| Highlight''' ==='''
| '''Equality operator''' is used to check whether a value lies in the range.

|-
| Highlight''' true'''
| We get the output as '''true s'''ince '''5 '''lies in the range '''1 '''to '''10. '''

|-
|
| <nowiki><<Pause>></nowiki>

This brings us to the end of this Spoken Tutorial.

|-
| Slide 11

Summary
| In this tutorial we have learnt

* Logical operator<br/> Ex: '''&&,||, !'''
* Parallel assignment<br/> Ex: a,b,c=10,20,30
* Range Operator<br/> Inclusive operator '''(..)'''<br/> Exclusive operator'''(...)'''

|-
| Slide 13

Assignment
| As an assignment

* Declare two variables using '''parallel assignment''' and
* Check whether their sum lies between '''20''' and '''50'''

using '''irb'''

|-
| Slide 14

About the Spoken Tutorial Project
| Watch the video available at the following link.

It summarises the Spoken Tutorial project.

If you do not have good bandwidth, you can download and watch it.

|-
| Slide 15
| The Spoken Tutorial Project Team :

Conducts workshops using spoken tutorials

Gives certificates to those who pass an online test

For more details, please write to

contact@spoken-tutorial.org

|-
| Slide 16

Acknowledgement
| Spoken Tutorial Project is a part of the Talk to a Teacher project.

It is supported by the National Mission on Education through ICT, MHRD, Government of India.

More information on this Mission is available at below link:

spoken-tutorial.org/NMEICT-Intro.

|-
| About the contributor Slide
| This script has been contributed by the Spoken Tutorial Team, IIT Bombay.

And the video has been contributed by Ruby Software Pvt. Ltd

[http://www.ruby-software.com/ http://www.ruby-software.com]

Thank you.

|}

@@ Line 14: / Line 14: @@
 |-
 | Slide 1
-| Welcome to this spoken tutorial on Logical & Other Operators
+| Welcome to this spoken tutorial on '''Logical & Other Operators'''.
 |-

@@ Line 57: / Line 57: @@
 Logical Operators are,
-* '''&& (and)'''
+* '''&& that is  (and)'''
-* '''|| (or)'''
+* '''||  that is (or)'''
-* '''! (not)'''
+* '''!  that is (not)'''
-|-
-| Slide 6
-−
-'''Logical operators'''
-−
-<nowiki>Eg : <Expresion1> </nowiki>'''&&'''<nowiki><Expression2></nowiki>
-−
-<nowiki><Expresion1> </nowiki>'''and'''<nowiki><Expression2></nowiki>
-−
-|  Here are examples of '''&&''' and '''and''' operators
 |-
@@ Line 84: / Line 75: @@
 |  Difference in the two forms is, '''precedence'''
-Symbolic '''and (&&) '''has higher '''precedence'''.
+Symbolic '''and   that is(&&) '''has higher '''precedence'''.
 |-
@@ Line 218: / Line 209: @@
 |  In '''expression 1 '''replace '''greater than''' sign with '''less than sign.'''
-And replace '''pipe '''symbol with word '''or.'''
+And replace '''pipe '''symbol with  the word '''or.'''
 Press '''Enter.'''
@@ Line 233: / Line 224: @@
 Since both the expressions are '''false,''' we get output as '''false'''.
 |-
 | Highlight '''<nowiki>!</nowiki>''' and '''not'''
-| <nowiki>!</nowiki>'''  '''not''' and ''' return the opposite value of the expression
+| <nowiki>!</nowiki>'''  ''' and ''' not ''' operator return the opposite value of the expression
 If the expression is '''true''', '''<nowiki>!</nowiki>''' operator will return a '''false''' value.
@@ Line 458: / Line 440: @@
 It consists of an start value, range of values and an end value.
-'''(..) '''two dot operator creates an '''inclusive range.'''
+'''(..) '''two dot operator creates '''inclusive range.'''
 '''(...) '''three dot operator creates an '''exclusive range.'''
@@ Line 555: / Line 537: @@
 Summary
-|  In this tutorial we have learnt
+|  In this tutorial, we have learnt
 * Logical operator<br/> Ex: '''&&,||, !'''

@@ Line 23: / Line 23: @@
 * Logical Operators
-* Parallel assignment
+* Parallel assignment and
 * Range Operators
@@ Line 110: / Line 110: @@
 |  Type
-'''3 greater than 2 space ampersand ampersand space 4 less than 5'''
+'''3 greater than 2 space double ampersand space 4 less than 5'''
 Press''' Enter'''
@@ Line 136: / Line 136: @@
 press '''Enter'''
-|  In '''expression 1 '''replace the double '''ampersand '''symbol''' '''with the word '''and.'''
+|  And  '''replace the double '''ampersand '''symbol''' '''with the word '''and.'''
 Press''' Enter'''
@@ Line 150: / Line 150: @@
 press '''Enter'''
-|  In '''expression 1 '''replace '''greater than''' sign with '''less than'''
+| Now press the up arrow key to get the previous command. In '''expression 1 '''replace '''greater than''' sign with '''less than'''
 Press''' Enter'''
@@ Line 170: / Line 170: @@
 |So, we get output as '''false'''.
 |-
@@ Line 190: / Line 180: @@
 | Difference in the two forms is '''precedence'''.
-Symbolic '''or''' ('''<nowiki>"||"</nowiki>''') has higher '''precedence'''.
+Symbolic '''or'''i.e ('''<nowiki>"||"</nowiki>''') has higher '''precedence'''.
 |-
@@ Line 226: / Line 216: @@
 press '''Enter'''
-|  In '''expression 1 '''replace '''greater than''' sign with '''less than.'''
+|  In '''expression 1 '''replace '''greater than''' sign with '''less than sign.'''
 And replace '''pipe '''symbol with word '''or.'''
@@ Line 255: / Line 245: @@
 |-
 | Highlight '''<nowiki>!</nowiki>''' and '''not'''
-|  '''not''' and '''<nowiki>!</nowiki>'''  return the opposite value of the expression
+| <nowiki>!</nowiki>'''  '''not''' and ''' return the opposite value of the expression
 If the expression is '''true''', '''<nowiki>!</nowiki>''' operator will return a '''false''' value.
@@ Line 265: / Line 255: @@
 |  Difference in the two forms is '''precedence'''.
-Symbolic '''not <nowiki>(!)</nowiki>''' has higher '''precedence'''.
+Symbolic '''not that is <nowiki>(!)</nowiki>''' has higher '''precedence'''.
 |-
@@ Line 310: / Line 300: @@
 |-
-| Press''' ctrl +l'''
+| Press''' ctrl +L'''
-|  Press '''Ctrl+l '''simultaneously to clear the''' irb''' console.
+|  Press '''Ctrl+L '''simultaneously to clear the''' irb''' console.
 |-
@@ Line 412: / Line 402: @@
 |  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 '''
+'''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 '''
 Press '''Enter.'''
@@ Line 530: / Line 520: @@
 |-
 | Highlight '''<nowiki>[1 ,2, 3, 4, 5, 6, 7, 8, 9]</nowiki>'''
-|  Here end value '''10''' is not included in the range.
+|  Here  the end value '''10''' is not included in the range.
 |-
@@ Line 569: / Line 559: @@
 * Logical operator<br/> Ex: '''&&,||, !'''
 * Parallel assignment<br/> Ex: a,b,c=10,20,30
-* Range Operator<br/> Inclusive operator '''(..)'''<br/> Exclusive operator'''(...)'''
+* Range Operator<br/> Inclusive operator '''(..) and  '''<br/> Exclusive operator'''(...)'''
 |-
@@ Line 589: / Line 579: @@
-It summarises the Spoken Tutorial project.
+It summaries the Spoken Tutorial project.
 If you do not have good bandwidth, you can download and watch it.

@@ Line 364: / Line 364: @@
 |  If we list multiple variables on the left hand side,
-then the array is unpacked and assigned into the respective variables.
+then the array is unpacked
 |-

@@ Line 2: / Line 2: @@
 '''Author:Spoken Tutorial Team, IIT Bombay'''
 Video: Shalini Nair, SNDT, Summer Intern 2013
 '''Keywords:logical operator, range operator, video tutorial'''

@@ Line 52: / Line 52: @@
 because they evaluate parts of an expression
-and return a '''true''' or  ''false''' value.
+and return a '''true''' or  '''false''' value.
 Logical Operators are,
@@ Line 63: / Line 63: @@
 | Slide 6
-Logical operators
+'''Logical operators'''
-−
-|  '''&&''' and '''and'''
 <nowiki>Eg : <Expresion1> </nowiki>'''&&'''<nowiki><Expression2></nowiki>
 <nowiki><Expresion1> </nowiki>'''and'''<nowiki><Expression2></nowiki>
 |-
@@ Line 87: / Line 87: @@
 |-
+|
-|  Lets us see some examples now.
+|  Let's us see some examples now.
 We will use '''irb '''for this.
@@ Line 172: / Line 172: @@
 | Slide 7
-|  '''<nowiki>||</nowiki>''' and '''or'''
+'''<nowiki>||</nowiki>''' and '''or'''
 <nowiki>Eg : <Expresion1></nowiki> '''||''' <nowiki><Expression2></nowiki>
 <nowiki><Expresion1></nowiki> '''or''' <nowiki><Expression2></nowiki>
 |-
@@ Line 243: / Line 245: @@
 | Slide 8
-|  '''<nowiki>!</nowiki>''' and '''not'''
+'''<nowiki>!</nowiki>''' and '''not'''
 Eg: '''<nowiki>!</nowiki>'''<Expression>
@@ Line 249: / Line 251: @@
 '''not'''<Expression>
 |-
 | Highlight '''<nowiki>!</nowiki>''' and '''not'''
@@ Line 322: / Line 325: @@
 |-
+|
-|  Lets switch to the '''terminal.'''
+|  Let's switch to the '''terminal.'''
 |-
@@ Line 448: / Line 451: @@
 |-
-| Slide
+| Slide '''Range'''
-−
 '''Range'''
 |  We will now learn about '''range''' in '''Ruby.'''
@@ Line 458: / Line 459: @@
 |-
-| Slide Sequence Range
+| Slide '''Sequence Range'''
 |  '''Sequence range''' is used to create a range of successive values.
@@ Line 468: / Line 469: @@
 |-
-| Slide Range Interval
+| Slide '''Range Interval'''
 |  Ranges are used to identify whether a value falls within a particular range, too.
@@ Line 482: / Line 483: @@
 |-
 | Type '''(1..10).to_a'''
-|  Type
+| Type
 '''Within brackets 1 two dots 10 then dot to underscore a'''
 |-
-| Highlight '''(1..10).to_a'''
+| Highlight '''..'''
 |  '''Two dot''' operator creates '''inclusive range. '''
-'''Inclusive operator''' includes both begin and end values in a range.
+|-
-Here '''to_a '''method is used to convert a '''range''' to a list.
+|-
 Press '''Enter.'''

@@ Line 478: / Line 478: @@
 |-
-| Highlight '''(1..10).to _a'''
+| Highlight '''(1..10).to_a'''
 |  '''Two dot''' operator creates '''inclusive range. '''
@@ Line 503: / Line 503: @@
 |-
-| Highlight '''(1...10).to _a'''
+| Highlight '''(1...10).to_a'''
 |  '''Three dot '''operator creates an '''exclusive range. '''