Difference between revisions of "PERL/C2/Hash-in-Perl/English-timed"

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|Welcome to the spoken tutorial on ''' Hash''' in '''Perl'''.

|Welcome to the spoken tutorial on ''' Hash''' in '''Perl'''.

|-

|-

| In this tutorial, we will learn about;  

| In this tutorial, we will learn about;  

|-

|-

|'''Hash'''  in '''Perl''' and  

|'''Hash'''  in '''Perl''' and  

   

   

|-

|-

| Accessing element of a '''hash'''  

| Accessing element of a '''hash'''  

    

    

|-

|-

|For this tutorial, I am using  

|For this tutorial, I am using  

   

   

|-

|-

| ''' Ubuntu Linux12.04''' operating system  

| ''' Ubuntu Linux12.04''' operating system  

|-

|-

|''' Perl 5.14.2''' and  

|''' Perl 5.14.2''' and  

|-

|-

| ''' gedit''' Text Editor  

| ''' gedit''' Text Editor  

|-

|-

|You can use any text editor of your choice.  

|You can use any text editor of your choice.  

   

   

|-

|-

|To practise this tutorial, you should have knowledge of ''' Variables & Data Structures''' in '''Perl.'''

|To practise this tutorial, you should have knowledge of ''' Variables & Data Structures''' in '''Perl.'''

   

   

|-

|-

| Knowledge of '''comments, loops, conditional statements''' and '''Arrays''' will be an added advantage.  

| Knowledge of '''comments, loops, conditional statements''' and '''Arrays''' will be an added advantage.  

   

   

|-

|-

|Please go through the relevant spoken tutorials on the ''' spoken tutorial''' website.  

|Please go through the relevant spoken tutorials on the ''' spoken tutorial''' website.  

|-

|-

|''' Hash''' is an unordered collection of data   

|''' Hash''' is an unordered collection of data   

|-

|-

|It's a ''' key/value pair data structure '''

|It's a ''' key/value pair data structure '''

|-

|-

| '''Hash keys''' are unique  

| '''Hash keys''' are unique  

|-

|-

|However, ''' Hash''' can have duplicate values  

|However, ''' Hash''' can have duplicate values  

|-

|-

| This is the declaration of a ''' hash''' .  

| This is the declaration of a ''' hash''' .  

   

   

|-

|-

|Let us see how to get the value of a ''' key''' from '''hash. '''

|Let us see how to get the value of a ''' key''' from '''hash. '''

|-

|-

|The syntax for accessing the value of a ''' key''' is  

|The syntax for accessing the value of a ''' key''' is  

   

   

|-

|-

|''' dollar hashName open curly bracket single quote keyName single quote close curly bracket'''

|''' dollar hashName open curly bracket single quote keyName single quote close curly bracket'''

   

   

|-

|-

| Let us understand ''' hash''' using a sample program.  

| Let us understand ''' hash''' using a sample program.  

   

   

|-

|-

|I have already typed the code in ''' perlHash dot pl''' file in '''gedit. '''

|I have already typed the code in ''' perlHash dot pl''' file in '''gedit. '''

|-

|-

|Type the code as shown in your ''' perlHash dot pl''' file.  

|Type the code as shown in your ''' perlHash dot pl''' file.  

   

   

|-

|-

| ''' Hash''' in ''' Perl''' is declared with '''percentage''' sign.  

| ''' Hash''' in ''' Perl''' is declared with '''percentage''' sign.  

|-

|-

| These are the keys of '''hash.'''

| These are the keys of '''hash.'''

   

   

|-

|-

|And these are the values of '''hash.'''   

|And these are the values of '''hash.'''   

    

    

|-

|-

|Note: To access ''' key''' of '''hash''', one has to use '''dollar''' sign.  

|Note: To access ''' key''' of '''hash''', one has to use '''dollar''' sign.  

   

   

|-

|-

|Press ''' Ctrl + S''' to save the file.  

|Press ''' Ctrl + S''' to save the file.  

   

   

|-

|-

|Then switch to  ''' terminal''' and execute the '''Perl script''' as  

|Then switch to  ''' terminal''' and execute the '''Perl script''' as  

   

   

|-

|-

|''' perl perlHash dot pl'''

|''' perl perlHash dot pl'''

|-

|-

|and press ''' Enter'''.

|and press ''' Enter'''.

|-

|-

| The output is as shown on the terminal.  

| The output is as shown on the terminal.  

|-

|-

|Now let us see add and delete of ''' keys''' from  '''hash.'''  

|Now let us see add and delete of ''' keys''' from  '''hash.'''  

   

   

|-

|-

|The syntax for .  

|The syntax for .  

|-

|-

|adding key is ''' dollar hashName open curly bracket '''

|adding key is ''' dollar hashName open curly bracket '''

|-

|-

|''' single quote KeyName single quote'''  

|''' single quote KeyName single quote'''  

|-

|-

|''' close curly bracket equal to $value semicolon'''  

|''' close curly bracket equal to $value semicolon'''  

   

   

|-

|-

|deleting key is ''' delete dollar hashName open curly bracket'''  

|deleting key is ''' delete dollar hashName open curly bracket'''  

|-

|-

|'''single quote KeyName single quote close curly bracket semicolon'''  

|'''single quote KeyName single quote close curly bracket semicolon'''  

   

   

|-

|-

| Now, let us understand this using a sample program.  

| Now, let us understand this using a sample program.  

   

   

|-

|-

| I have already typed the code in ''' hashKeyOperations dot pl''' file.  

| I have already typed the code in ''' hashKeyOperations dot pl''' file.  

   

   

|-

|-

| This is the declaration of ''' hash.'''

| This is the declaration of ''' hash.'''

   

   

|-

|-

|We'll be adding, deleting the ''' keys''' from this ''' hash.'''

|We'll be adding, deleting the ''' keys''' from this ''' hash.'''

   

   

|-

|-

| Here we are adding a '''key''' to an already created '''hash.'''

| Here we are adding a '''key''' to an already created '''hash.'''

   

   

|-

|-

|It is like assigning a value to a variable.  

|It is like assigning a value to a variable.  

|-

|-

|''' delete''' keyword is used to delete the ''' key.'''  

|''' delete''' keyword is used to delete the ''' key.'''  

   

   

|-

|-

|We need to pass the '''key''' to delete it.  

|We need to pass the '''key''' to delete it.  

   

   

|-

|-

| Press ''' Ctrl+S''' to save the file.  

| Press ''' Ctrl+S''' to save the file.  

   

   

|-

|-

|Switch to the terminal and execute the ''' Perl script''' as  

|Switch to the terminal and execute the ''' Perl script''' as  

   

   

|-

|-

| ''' perl hashKeyOperations dot pl'''  

| ''' perl hashKeyOperations dot pl'''  

   

   

|-

|-

|  and press ''' Enter.'''

|  and press ''' Enter.'''

   

   

|-

|-

| Output will be as shown on the terminal.

| Output will be as shown on the terminal.

   

   

|-

|-

| Let us look at ''' sorting''' of a ''' hash keys''' and '''values.'''

| Let us look at ''' sorting''' of a ''' hash keys''' and '''values.'''

|-

|-

| Syntax to ''' sort keys''' is  

| Syntax to ''' sort keys''' is  

|-

|-

|''' sort open bracket keys percentage hashName close bracket semicolon '''

|''' sort open bracket keys percentage hashName close bracket semicolon '''

   

   

|-

|-

|Similarly, we can '''sort hash values''' as  

|Similarly, we can '''sort hash values''' as  

|-

|-

|''' sort open bracket values percentage hashName close bracket semicolon'''  

|''' sort open bracket values percentage hashName close bracket semicolon'''  

   

   

|-

|-

|Let us understand ''' sorting''' functionality using a sample program.   

|Let us understand ''' sorting''' functionality using a sample program.   

|-

|-

|Let me switch to ''' sortHash dot pl'''  on ''' gedit.'''

|Let me switch to ''' sortHash dot pl'''  on ''' gedit.'''

   

   

|-

|-

|Type the code as displayed on the screen in your ''' sortHash dot pl''' file.  

|Type the code as displayed on the screen in your ''' sortHash dot pl''' file.  

|-

|-

| Here we have declared ''' hash''' of '''address. '''

| Here we have declared ''' hash''' of '''address. '''

   

   

|-

|-

|Here, to sort the ''' keys''' we have used the '''sort''' inbuilt function, along with the '''keys''' function.  

|Here, to sort the ''' keys''' we have used the '''sort''' inbuilt function, along with the '''keys''' function.  

|-

|-

|This will sort the '''hash keys''' in alphabetical order.  

|This will sort the '''hash keys''' in alphabetical order.  

   

   

|-

|-

|Similarly, we can use the '''sort''' function on '''values''' of '''hash.'''  

|Similarly, we can use the '''sort''' function on '''values''' of '''hash.'''  

|-

|-

|Sorting can also be done on ''' numeric keys''' and/or '''values.'''  

|Sorting can also be done on ''' numeric keys''' and/or '''values.'''  

   

   

|-

|-

|Save the file and switch to terminal.  

|Save the file and switch to terminal.  

|-

|-

|Execute the script by typing ''' perl sortHash dot pl''' and Press ''' Enter '''

|Execute the script by typing ''' perl sortHash dot pl''' and Press ''' Enter '''

|-

|-

|The output will be as shown on the terminal.

|The output will be as shown on the terminal.

   

   

|-

|-

|Now, let us see how to get all ''' keys ''' and ''' values''' of '''hash.'''

|Now, let us see how to get all ''' keys ''' and ''' values''' of '''hash.'''

|-

|-

|''' Perl''' provides inbuilt ''' function''' to fetch all the ''' hash keys''' and ''' values.'''  

|''' Perl''' provides inbuilt ''' function''' to fetch all the ''' hash keys''' and ''' values.'''  

   

   

|-

|-

|''' keys function''' is used to retrive all the ''' keys''' of ''' hash '''

|''' keys function''' is used to retrive all the ''' keys''' of ''' hash '''

   

   

|-

|-

| ''' values''' function returns ''' values''' of all the ''' keys''' whereas  

| ''' values''' function returns ''' values''' of all the ''' keys''' whereas  

   

   

|-

|-

| ''' each''' function iterates over ''' hash''' and returns ''' key/value''' pair from ''' hash'''  

| ''' each''' function iterates over ''' hash''' and returns ''' key/value''' pair from ''' hash'''  

|-

|-

| Let us understand these  using a sample program.  

| Let us understand these  using a sample program.  

   

   

|-

|-

| For this, we'll use '''perlHash dot pl''' script, which we have created earlier in this tutorial.  

| For this, we'll use '''perlHash dot pl''' script, which we have created earlier in this tutorial.  

|-

|-

| Type the following piece of code as shown on the screen;  

| Type the following piece of code as shown on the screen;  

|-

|-

| Let us understand the code now.  

| Let us understand the code now.  

|-

|-

|''' keys''' function on ''' hash''', returns an '''array''' which contains all '''keys''' of '''hash.'''

|''' keys''' function on ''' hash''', returns an '''array''' which contains all '''keys''' of '''hash.'''

   

   

|-

|-

|  ''' values''' function on ''' hash''' returns an '''array''' of '''values''' for all '''keys''' of '''hash'''.

|  ''' values''' function on ''' hash''' returns an '''array''' of '''values''' for all '''keys''' of '''hash'''.

   

   

|-

|-

| ''' each'''  function returns the ''' key/value''' pair.  

| ''' each'''  function returns the ''' key/value''' pair.  

|-

|-

|Here, we have used the ''' while loop.'''

|Here, we have used the ''' while loop.'''

|-

|-

|It will iterate over each ''' key/value''' pair of ''' hash,''' that is returned by '''each function'''.

|It will iterate over each ''' key/value''' pair of ''' hash,''' that is returned by '''each function'''.

|-

|-

| Press ''' Ctrl+S''' to save the file.  

| Press ''' Ctrl+S''' to save the file.  

|-

|-

|Now, let us execute the script on the terminal by typing  

|Now, let us execute the script on the terminal by typing  

   

   

|-

|-

| ''' perl perlHash dot pl'''  

| ''' perl perlHash dot pl'''  

|-

|-

| And Press ''' Enter'''

| And Press ''' Enter'''

|-

|-

| The following output will be seen on the terminal.

| The following output will be seen on the terminal.

   

   

|-

|-

|Now let us see few other ways of looping over ''' hash.'''

|Now let us see few other ways of looping over ''' hash.'''

   

   

|-

|-

| We can use ''' foreach loop''' to iterate over each '''key''' of '''hash'''.  

| We can use ''' foreach loop''' to iterate over each '''key''' of '''hash'''.  

   

   

|-

|-

|Then perform a set of actions on the value of a key.

|Then perform a set of actions on the value of a key.

   

   

|-

|-

|The syntax is as displayed on the screen.  

|The syntax is as displayed on the screen.  

 

 

|-

|-

| Here, each iteration of ''' foreach loop''' will assign '''key''' from ''' hash''' to ''' $variable.'''

| Here, each iteration of ''' foreach loop''' will assign '''key''' from ''' hash''' to ''' $variable.'''

|-

|-

|Then it will use that ''' $variable''' to fetch the  value or to perform a set of actions.  

|Then it will use that ''' $variable''' to fetch the  value or to perform a set of actions.  

|-

|-

| Similarly, we can loop over '''hash values''' as shown on the screen.  

| Similarly, we can loop over '''hash values''' as shown on the screen.  

|-

|-

|We will look at sample program.  

|We will look at sample program.  

   

   

|-

|-

|So, let me switch to ''' loopingOverHash dot pl''' in '''gedit.'''

|So, let me switch to ''' loopingOverHash dot pl''' in '''gedit.'''

|-

|-

| Type the following piece of code as shown in your ''' loopingOverHash dot pl'''  

| Type the following piece of code as shown in your ''' loopingOverHash dot pl'''  

|-

|-

|This piece of code returns single ''' key''' of '''hash.'''

|This piece of code returns single ''' key''' of '''hash.'''

|-

|-

|Here in our case,  

|Here in our case,  

|-

|-

|1st time ''' dollar key ($key)''' contains the ''' Department''' as ''' key.'''  

|1st time ''' dollar key ($key)''' contains the ''' Department''' as ''' key.'''  

|-

|-

|In the next iteration of '''foreach, Name key''' is returned.  

|In the next iteration of '''foreach, Name key''' is returned.  

|-

|-

|Note: ''' Hash''' is an unordered collection of data.  

|Note: ''' Hash''' is an unordered collection of data.  

|-

|-

|So, ''' keys''' returned will not be in the sequence defined at the time of creating '''hash.'''  

|So, ''' keys''' returned will not be in the sequence defined at the time of creating '''hash.'''  

|-

|-

| The loop on ''' values''' works in a similar way.  

| The loop on ''' values''' works in a similar way.  

|-

|-

|Press ''' Ctrl + S''' to save the file.  

|Press ''' Ctrl + S''' to save the file.  

|-

|-

|Then, switch to terminal and execute the ''' Perl script''' as  

|Then, switch to terminal and execute the ''' Perl script''' as  

|-

|-

|''' perl loopingOverHash dot pl'''  

|''' perl loopingOverHash dot pl'''  

|-

|-

|and press ''' Enter.'''

|and press ''' Enter.'''

|-

|-

|The following output is displayed on the terminal.

|The following output is displayed on the terminal.

|-

|-

|Let us summarize.  

|Let us summarize.  

|-

|-

|In this tutorial, we learnt -  

|In this tutorial, we learnt -  

|-

|-

|''' Hash''' in '''Perl''' and  

|''' Hash''' in '''Perl''' and  

|-

|-

|Accessing elements of a '''hash'''  

|Accessing elements of a '''hash'''  

|-

|-

|using sample programs.  

|using sample programs.  

|-

|-

|Here is assignment for you -  

|Here is assignment for you -  

|-

|-

|Declare '''hash''' having '''student name''' as''' key'''  

|Declare '''hash''' having '''student name''' as''' key'''  

|-

|-

|And '''his/her percentage''' as the '''value'''.  

|And '''his/her percentage''' as the '''value'''.  

|-

|-

|Loop over '''hash''' using '''keys, values''' and '''each''' function  

|Loop over '''hash''' using '''keys, values''' and '''each''' function  

|-

|-

|Then print the ''' percentage''' of each student.  

|Then print the ''' percentage''' of each student.  

|-

|-

|Watch the video available at the following link

|Watch the video available at the following link

   

   

|-

|-

|It summaries the Spoken Tutorial project

|It summaries 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  Conducts workshops using spoken tutorials

|  The Spoken Tutorial Project Team  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 at spoken hyphen tutorial dot org

|For more details, please write to contact at spoken hyphen tutorial dot 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

   

   

|-

|-

|  Hope you enjoyed this Perl tutorial.  

|  Hope you enjoyed this Perl tutorial.  

   

   

|-

|-

|This is Amol signing off.

|This is Amol signing off.

   

   

|-

|-

|Thanks for joining.

|Thanks for joining.

   

   

|}

|}