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

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{| border=1

|| '''Narration'''

|| '''Narration'''

|-

|-

| Welcome to this spoken tutorial on '''Logical & Other Operators. '''

| Welcome to this spoken tutorial on '''Logical & Other Operators. '''

|-

|-

| In this tutorial we will learn  

| In this tutorial we will learn  

|-

|-

| '''Logical Operators '''

| '''Logical Operators '''

|-

|-

|'''Parallel assignment''' and  

|'''Parallel assignment''' and  

|-

|-

| '''Range Operators '''

| '''Range Operators '''

|-

|-

|Here we are using  

|Here we are using  

|-

|-

| '''Ubuntu Linux''' version 12.04  

| '''Ubuntu Linux''' version 12.04  

|-

|-

|  ''' Ruby 1.9.3  '''

|  ''' Ruby 1.9.3  '''

|-

|-

|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'''.  

|-

|-

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

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

    

    

|-

|-

| If not, for relevant tutorials, please visit our website  

| If not, for relevant tutorials, please visit our website  

|-

|-

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

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

|-

|-

|  because they evaluate parts of an expression  

|  because they evaluate parts of an expression  

|-

|-

|and return a ''' true''' or ''' false''' value.  

|and return a ''' true''' or ''' false''' value.  

|-

|-

|'''Logical Operators''' are,  

|'''Logical Operators''' are,  

|-

|-

| ''' double ampersand (&&)'''  that is '''(and)'''  

| ''' double ampersand (&&)'''  that is '''(and)'''  

|-

|-

| ''' double pipe '''  that is '''(or)'''  

| ''' double pipe '''  that is '''(or)'''  

|-

|-

|''' Exclamation (!)'''  that is '''(not)'''  

|''' Exclamation (!)'''  that is '''(not)'''  

|-

|-

|  '''&&(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.'''  

|-

|-

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

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

|-

|-

| Difference in the two forms is, precedence

| Difference in the two forms is, precedence

|-

|-

|Symbolic '''and'''  that is'''&&(double ampersand)''' has higher precedence.  

|Symbolic '''and'''  that is'''&&(double ampersand)''' has higher precedence.  

|-

|-

|Let's us see some examples now.  

|Let's us see some examples now.  

|-

|-

|We will use '''irb''' for this.  

|We will use '''irb''' for this.  

|-

|-

|  Open the ''' terminal''' by pressing '''Ctrl, Alt and T''' keys simultaneously.  

|  Open the ''' terminal''' by pressing '''Ctrl, Alt and T''' keys simultaneously.  

|-

|-

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

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

|-

|-

| 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'''  

|-

|-

| Press ''' Enter'''

| Press ''' Enter'''

|-

|-

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

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

|-

|-

|Here, '''expression1'''  that is 3>2 is '''true'''.  

|Here, '''expression1'''  that is 3>2 is '''true'''.  

|-

|-

|'''Expression 2''' that is 4<5 is also '''true.'''  

|'''Expression 2''' that is 4<5 is also '''true.'''  

|-

|-

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

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

|-

|-

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

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

|-

|-

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

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

|-

|-

|  Press '''Enter '''

|  Press '''Enter '''

|-

|-

|We get the same result.   

|We get the same result.   

|-

|-

| Now press up arrow key again to get the previous command.  

| Now press up arrow key again to get the previous command.  

|-

|-

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

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

|-

|-

|Press ''' Enter '''

|Press ''' Enter '''

|-

|-

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

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

|-

|-

|This is because ''' 3<2''' is '''false.'''

|This is because ''' 3<2''' is '''false.'''

|-

|-

| 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.   

|-

|-

| So, we get output as '''false.'''  

| So, we get output as '''false.'''  

|-

|-

| ''' double pipe''' and '''or''' evaluate to '''true''', if either '''expression''' is '''true.'''  

| ''' double pipe''' and '''or''' evaluate to '''true''', if either '''expression''' is '''true.'''  

|-

|-

|Second expression is evaluated only if first is '''false.'''  

|Second expression is evaluated only if first is '''false.'''  

|-

|-

|Difference in the two forms is '''precedence.'''  

|Difference in the two forms is '''precedence.'''  

|-

|-

|Symbolic '''or''' i.e ''' double pipe''' has higher '''precedence.'''  

|Symbolic '''or''' i.e ''' double pipe''' has higher '''precedence.'''  

|-

|-

|  Now, let's try some examples.   

|  Now, let's try some examples.   

|-

|-

|''' 10 greater than 6 space double pipe space 12 less than 7'''

|''' 10 greater than 6 space double pipe space 12 less than 7'''

|-

|-

| Press  '''Enter.'''  

| Press  '''Enter.'''  

|-

|-

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

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

|-

|-

|Here '''expression 1''' that is '''10>6''' is '''true'''.

|Here '''expression 1''' that is '''10>6''' is '''true'''.

|-

|-

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

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

|-

|-

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

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

|-

|-

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

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

|-

|-

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

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

|-

|-

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

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

|-

|-

|  Press '''Enter.'''  

|  Press '''Enter.'''  

|-

|-

|Here, '''expression1''' that is 10<6 is '''false. '''

|Here, '''expression1''' that is 10<6 is '''false. '''

|-

|-

| '''Expression 2''' that is 12<7 is also '''false. '''

| '''Expression 2''' that is 12<7 is also '''false. '''

|-

|-

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

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

|-

|-

|'''! (exclamation mark )''' and '''not''' operators return the opposite value of the expression  

|'''! (exclamation mark )''' and '''not''' operators return the opposite value of the expression  

|-

|-

|  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.  

|-

|-

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

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

|-

|-

| Difference in the two forms is '''precedence. '''

| Difference in the two forms is '''precedence. '''

|-

|-

| Symbolic '''not that is (!)'''  has higher '''precedence.'''  

| Symbolic '''not that is (!)'''  has higher '''precedence.'''  

|-

|-

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

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

|-

|-

|First type ''' 10 double equal to 10'''

|First type ''' 10 double equal to 10'''

|-

|-

|  Press '''Enter '''

|  Press '''Enter '''

|-

|-

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

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

|-

|-

|To invert the result of above expression,  

|To invert the result of above expression,  

|-

|-

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

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

|-

|-

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

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

|-

|-

| Press '''Enter. '''

| Press '''Enter. '''

|-

|-

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

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

|-

|-

| Press '''Ctrl+L''' simultaneously to clear the '''irb''' console.  

| Press '''Ctrl+L''' simultaneously to clear the '''irb''' console.  

|-

|-

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

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

|-

|-

|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. '''

|-

|-

| Let's switch to the '''terminal.'''

| Let's switch to the '''terminal.'''

|-

|-

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

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

|-

|-

| 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 '''

|-

|-

| and press '''Enter. '''

| and press '''Enter. '''

|-

|-

|Here, '''10''' will be assigned to variable '''a '''

|Here, '''10''' will be assigned to variable '''a '''

|-

|-

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

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

|-

|-

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

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

|-

|-

|The right hand side acts as an '''array'''.  

|The right hand side acts as an '''array'''.  

|-

|-

|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.  

|-

|-

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

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

|-

|-

| For now, let's check whether the '''assignment''' is done properly.  

| For now, let's check whether the '''assignment''' is done properly.  

|-

|-

| Type '''a''' and press '''Enter.'''

| Type '''a''' and press '''Enter.'''

|-

|-

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

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

|-

|-

|Type '''b''' and press '''Enter.'''

|Type '''b''' and press '''Enter.'''

|-

|-

|We get 20  

|We get 20  

|-

|-

| Type '''c''' and press '''Enter.'''

| Type '''c''' and press '''Enter.'''

|-

|-

|30 is displayed.  

|30 is displayed.  

|-

|-

|  '''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.  

|-

|-

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

|Let us swap the values of variables a and 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'''  

|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. '''

| Press '''Enter. '''

|-

|-

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

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

|-

|-

|'''b=20 '''

|'''b=20 '''

|-

|-

|Now let's swap a and b.

|Now let's swap a and b.

|-

|-

|To do so type  

|To do so type  

|-

|-

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

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

|-

|-

|Press '''Enter.'''  

|Press '''Enter.'''  

|-

|-

| 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.'''

|-

|-

|  We get the output as  

|  We get the output as  

|-

|-

|'''a=20 '''

|'''a=20 '''

|-

|-

| '''b=10 '''

| '''b=10 '''

|-

|-

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

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

|-

|-

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

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

|-

|-

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

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

|-

|-

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

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

|-

|-

|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.  

|-

|-

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

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

|-

|-

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

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

|-

|-

|'''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.  

|-

|-

|We do this using (===) the '''equality''' operator.   

|We do this using (===) the '''equality''' operator.   

|-

|-

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

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

|-

|-

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

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

|-

|-

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

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

|-

|-

|'''Two dot''' operator creates '''inclusive range. '''

|'''Two dot''' operator creates '''inclusive range. '''

|-

|-

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

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

|-

|-

|Press '''Enter. '''

|Press '''Enter. '''

|-

|-

|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.  

|-

|-

|Now we will see an '''exclusive range''' operator.  

|Now we will see an '''exclusive range''' operator.  

|-

|-

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

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

|-

|-

|'''Three dot''' operator creates an '''exclusive range. '''

|'''Three dot''' operator creates an '''exclusive range. '''

|-

|-

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

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

|-

|-

|Press '''Enter. '''

|Press '''Enter. '''

|-

|-

|Here the end value 10 is not included in the range.  

|Here the end value 10 is not included in the range.  

|-

|-

|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.  

|-

|-

|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 '''

|-

|-

|Press '''Enter. '''

|Press '''Enter. '''

|-

|-

|'''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.  

|-

|-

|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.  

|-

|-

|This brings us to the end of this Spoken Tutorial.  

|This brings us to the end of this Spoken Tutorial.  

|-

|-

|In this tutorial, we have learnt  

|In this tutorial, we have learnt  

|-

|-

|'''Logical operator''' i.e ''' double ampersand, double pipe and exclamation mark operators '''

|'''Logical operator''' i.e ''' double ampersand, double pipe and exclamation mark operators '''

|-

|-

|'''Parallel assignment''' Ex: a,b,c=10,20,30  

|'''Parallel assignment''' Ex: a,b,c=10,20,30  

|-

|-

|'''Range Operator  Inclusive operator '''(..) and Exclusive operator(...)'''

|'''Range Operator  Inclusive operator '''(..) and Exclusive operator(...)'''

|-

|-

|As an assignment  

|As an assignment  

|-

|-

|Declare two variables using '''parallel assignment''' and  

|Declare two variables using '''parallel assignment''' and  

|-

|-

|Check whether their sum lies between 20 and 50  

|Check whether their sum lies between 20 and 50  

|-

|-

|  Watch the video available at the following link.

|  Watch the video available at the following link.

|-

|-

|It summarises the Spoken Tutorial project.

|It summarises the Spoken Tutorial project.

|-

|-

|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.  

|-

|-

|  The Spoken Tutorial Project Team :

|  The Spoken Tutorial Project Team :

|-   

|-   

|Conducts workshops using spoken tutorials  

|Conducts workshops using spoken tutorials  

|-

|-

|Gives certificates to those who pass an online test  

|Gives certificates to those who pass an online test  

|-

|-

|For more details, please write to contact@spoken-tutorial.org

|For more details, please write to contact@spoken-tutorial.org

|-

|-

|  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.

|-

|-

|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.

|-

|-

|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

|-

|-

|This script has been contributed by the spoken tutorial team IIT Bombay  

|This script has been contributed by the spoken tutorial team IIT Bombay  

|-

|-

|And this is Shalini Nair signing off  Thank you  

|And this is Shalini Nair signing off  Thank you  

|}

|}