Difference between revisions of "PERL/C2/Hash-in-Perl/English-timed"
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{| border=1 | {| border=1 | ||
− | + | |'''Time''' | |
− | + | |'''Narration''' | |
|- | |- | ||
− | | 00 | + | | 00:01 |
− | |Welcome to the spoken tutorial on ''' Hash''' in ''' | + | |Welcome to the '''spoken tutorial''' on '''Hash''' in '''PERL'''. |
|- | |- | ||
− | | 00 | + | | 00:05 |
− | | In this tutorial, we will learn about | + | | In this tutorial, we will learn about: |
|- | |- | ||
− | |00 | + | |00:09 |
− | |'''Hash''' | + | |'''Hash''' in PERL and |
|- | |- | ||
− | |00 | + | |00:11 |
− | | | + | | accessing an '''element''' of a '''hash'''. |
|- | |- | ||
− | |00 | + | |00:14 |
− | |For this tutorial, I am using | + | |For this tutorial, I am using: |
|- | |- | ||
− | | 00 | + | | 00:16 |
− | | ''' Ubuntu | + | | '''Ubuntu Linux 12.04''' operating system |
|- | |- | ||
− | | 00 | + | | 00:21 |
− | |''' Perl 5.14.2''' and | + | | '''Perl 5.14.2''' and |
|- | |- | ||
− | | 00 | + | | 00:24 |
− | | ''' gedit''' Text Editor | + | | ''' gedit''' Text Editor. |
|- | |- | ||
− | |00 | + | |00:26 |
|You can use any text editor of your choice. | |You can use any text editor of your choice. | ||
|- | |- | ||
− | |00 | + | |00:30 |
− | |To | + | |To practice this tutorial, you should have knowledge of '''variables''' & '''data Structures''' in PERL. |
|- | |- | ||
− | | 00 | + | | 00:38 |
− | | Knowledge of '''comments, loops, conditional statements''' and ''' | + | | Knowledge of '''comments, loops, conditional statements''' and '''arrays''' will be an added advantage. |
|- | |- | ||
− | |00 | + | |00:46 |
− | |Please go through the relevant spoken tutorials on the ''' | + | |Please go through the relevant spoken tutorials on the '''Spoken Tutorial''' website. |
|- | |- | ||
− | |00 | + | |00:52 |
− | |''' Hash''' is an unordered collection of data | + | |'''Hash''' is an unordered collection of data. |
|- | |- | ||
− | |00 | + | |00:56 |
− | |It's a ''' key/value pair data structure ''' | + | |It's a '''key/value''' pair '''data structure'''. |
|- | |- | ||
− | | 00 | + | | 00:59 |
− | | '''Hash | + | | '''Hash''' keys are unique. |
|- | |- | ||
− | |01 | + | |01:01 |
− | |However, ''' Hash''' can have duplicate values | + | |However, '''Hash''' can have duplicate values. |
|- | |- | ||
− | |01 | + | |01:05 |
− | | This is the declaration of a ''' hash''' . | + | | This is the declaration of a '''hash'''. |
|- | |- | ||
− | |01 | + | |01:08 |
− | |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.''' |
|- | |- | ||
− | |01 | + | |01:12 |
− | |The syntax for accessing the value of a ''' key''' is | + | |The syntax for accessing the value of a ''' key''' is: |
|- | |- | ||
− | |01 | + | |01:17 |
− | |''' 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'''. |
|- | |- | ||
− | |01 | + | |01:26 |
| Let us understand ''' hash''' using a sample program. | | Let us understand ''' hash''' using a sample program. | ||
|- | |- | ||
− | | 01 | + | | 01:31 |
− | |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.''' |
|- | |- | ||
− | |01 | + | |01:37 |
|Type the code as shown in your ''' perlHash dot pl''' file. | |Type the code as shown in your ''' perlHash dot pl''' file. | ||
|- | |- | ||
− | |01 | + | |01:42 |
− | | ''' Hash''' in | + | | '''Hash''' in PERL is declared with '''percentage''' sign (%). |
|- | |- | ||
− | | 01 | + | | 01:47 |
− | | These are the keys of '''hash | + | | These are the keys of '''hash''' |
|- | |- | ||
− | |01 | + | |01:49 |
− | | | + | |and these are the values of '''hash.''' |
|- | |- | ||
− | |01 | + | |01:53 |
− | |Note: To access ''' key''' of '''hash''', one has to use | + | |Note: To access '''key''' of a '''hash''', one has to use dollar sign. |
|- | |- | ||
− | |01 | + | |01:59 |
− | |Press ''' Ctrl + S''' to save the file. | + | |Press '''Ctrl + S''' to '''save''' the file. |
|- | |- | ||
− | |02 | + | |02:02 |
− | |Then switch to | + | |Then switch to '''terminal''' and execute the '''Perl script''' as: |
|- | |- | ||
− | |02 | + | |02:08 |
− | |''' perl perlHash dot pl''' | + | |'''perl perlHash dot pl''' |
|- | |- | ||
− | |02 | + | |02:11 |
− | |and press ''' Enter'''. | + | |and press '''Enter'''. |
|- | |- | ||
− | |02 | + | |02:14 |
| The output is as shown on the terminal. | | The output is as shown on the terminal. | ||
|- | |- | ||
− | |02 | + | |02:19 |
− | |Now let us see add and delete of ''' keys''' from '''hash.''' | + | |Now, let us see add and delete of '''keys''' from '''hash.''' |
|- | |- | ||
− | |02 | + | |02:24 |
− | |The syntax for | + | |The '''syntax''' for: |
|- | |- | ||
− | |02 | + | |02:26 |
− | | | + | | Adding key is- '''dollar hashName open curly bracket''' |
|- | |- | ||
− | |02 | + | |02:30 |
− | |''' single quote KeyName single quote''' | + | |'''single quote KeyName single quote''' |
|- | |- | ||
− | |02 | + | |02:34 |
− | |''' close curly bracket equal to $value semicolon''' | + | |'''close curly bracket equal to $value semicolon'''. |
|- | |- | ||
− | |02 | + | |02:40 |
− | | | + | | Deleting key is- '''delete dollar hashName open curly bracket''' |
|- | |- | ||
− | |02 | + | |02:46 |
− | |'''single quote KeyName single quote close curly bracket semicolon''' | + | |'''single quote KeyName single quote close curly bracket semicolon'''. |
|- | |- | ||
− | | 02 | + | | 02:53 |
| Now, let us understand this using a sample program. | | Now, let us understand this using a sample program. | ||
|- | |- | ||
− | | 02 | + | | 02:58 |
| I have already typed the code in ''' hashKeyOperations dot pl''' file. | | I have already typed the code in ''' hashKeyOperations dot pl''' file. | ||
|- | |- | ||
− | | 03 | + | | 03:05 |
− | | This is the declaration of ''' hash.''' | + | | This is the declaration of a '''hash.''' |
|- | |- | ||
− | |03 | + | |03:08 |
− | |We | + | |We will be adding, deleting the ''' keys''' from this ''' hash.''' |
|- | |- | ||
− | | 03 | + | | 03:13 |
| Here we are adding a '''key''' to an already created '''hash.''' | | Here we are adding a '''key''' to an already created '''hash.''' | ||
|- | |- | ||
− | | 03 | + | | 03:18 |
− | |It is like assigning a value to a variable. | + | |It is like assigning a value to a '''variable'''. |
|- | |- | ||
− | |03 | + | |03:23 |
− | |''' delete''' keyword is used to delete the ''' key.''' | + | |'''delete''' keyword is used to delete the '''key.''' |
|- | |- | ||
− | |03 | + | |03:27 |
|We need to pass the '''key''' to delete it. | |We need to pass the '''key''' to delete it. | ||
|- | |- | ||
− | | | + | | 03:31 |
− | | Press ''' Ctrl+S''' to save the file. | + | | Press ''' Ctrl+S''' to '''save''' the file. |
|- | |- | ||
− | |03 | + | |03:35 |
− | |Switch to the terminal and execute the ''' Perl script''' as | + | |Switch to the '''terminal''' and '''execute''' the ''' Perl script''' as: |
|- | |- | ||
− | | | + | | 03:40 |
| ''' perl hashKeyOperations dot pl''' | | ''' perl hashKeyOperations dot pl''' | ||
|- | |- | ||
− | | | + | | 03:44 |
− | | and press ''' Enter.''' | + | | and press '''Enter.''' |
|- | |- | ||
− | | 03 | + | | 03:47 |
| Output will be as shown on the terminal. | | Output will be as shown on the terminal. | ||
|- | |- | ||
− | | 03 | + | | 03:52 |
− | | Let us look at | + | | Let us look at sorting of '''hash keys''' and '''values.''' |
|- | |- | ||
− | | 03 | + | | 03:57 |
− | | Syntax to ''' sort keys''' is | + | | Syntax to '''sort''' '''keys''' is: |
|- | |- | ||
− | |04 | + | |04:00 |
− | |''' sort open bracket keys percentage hashName close bracket semicolon ''' | + | |'''sort open bracket keys percentage hashName close bracket semicolon'''. |
|- | |- | ||
− | |04 | + | |04:07 |
− | |Similarly, we can ''' | + | |Similarly, we can sort '''hash values''' as: |
|- | |- | ||
− | |04 | + | |04:11 |
− | |''' sort open bracket values percentage hashName close bracket semicolon''' | + | |'''sort open bracket values percentage hashName close bracket semicolon'''. |
|- | |- | ||
− | |04 | + | |04:18 |
− | |Let us understand | + | |Let us understand sorting functionality using a sample program. |
|- | |- | ||
− | |04 | + | |04:24 |
− | |Let me switch to ''' sortHash dot pl''' on ''' gedit.''' | + | |Let me switch to ''' sortHash dot pl''' on '''gedit.''' |
|- | |- | ||
− | | 04 | + | | 04:30 |
− | |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. |
|- | |- | ||
− | | 04 | + | | 04:36 |
− | | Here we have declared ''' hash''' of '''address. ''' | + | | Here, we have declared '''hash''' of '''address.''' |
|- | |- | ||
− | |04 | + | |04:41 |
− | |Here, to sort the ''' keys''' we have used the '''sort''' inbuilt function | + | |Here, to sort the '''keys''', we have used the '''sort''' inbuilt function along with the '''keys''' function. |
|- | |- | ||
− | |04 | + | |04:49 |
|This will sort the '''hash keys''' in alphabetical order. | |This will sort the '''hash keys''' in alphabetical order. | ||
|- | |- | ||
− | |04 | + | |04:54 |
|Similarly, we can use the '''sort''' function on '''values''' of '''hash.''' | |Similarly, we can use the '''sort''' function on '''values''' of '''hash.''' | ||
|- | |- | ||
− | |04 | + | |04:59 |
− | |Sorting can also be done on | + | |Sorting can also be done on numeric keys and/or values. |
|- | |- | ||
− | |05 | + | |05:05 |
− | |Save the file and switch to terminal. | + | |'''Save''' the file and switch to terminal. |
|- | |- | ||
− | |05 | + | |05:09 |
− | |Execute the script by typing ''' perl sortHash dot pl''' and | + | |Execute the script by typing ''' perl sortHash dot pl''' and press '''Enter'''. |
|- | |- | ||
− | |05 | + | |05:17 |
|The output will be as shown on the terminal. | |The output will be as shown on the terminal. | ||
|- | |- | ||
− | |05 | + | |05:22 |
− | |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 a '''hash.''' |
|- | |- | ||
− | | 05 | + | | 05:27 |
− | | | + | |PERL provides inbuilt function to fetch all the '''hash keys''' and '''values.''' |
|- | |- | ||
− | | 05 | + | | 05:34 |
− | |''' keys | + | |'''keys()''' function is used to retrieve all the keys of a '''hash''', |
|- | |- | ||
− | |05 | + | |05:40 |
− | | ''' values''' function returns ''' values''' of all the ''' keys''' whereas | + | | '''values()''' function returns '''values''' of all the '''keys''' whereas |
|- | |- | ||
− | | 05 | + | | 05:46 |
− | | ''' each''' function iterates over ''' hash''' and returns ''' key/value''' pair from ''' hash''' | + | | '''each()''' function iterates over ''' hash''' and returns '''key/value''' pair from ''' hash'''. |
|- | |- | ||
− | | 05 | + | | 05:53 |
− | | Let us understand these | + | | Let us understand these using a sample program. |
|- | |- | ||
− | | 05 | + | | 05:57 |
− | | For this, we'll use '''perlHash dot pl''' script | + | | For this, we'll use '''perlHash dot pl''' script which we have created earlier in this tutorial. |
|- | |- | ||
− | | 06 | + | | 06:07 |
− | | Type the following piece of code as shown on the screen | + | | Type the following piece of code as shown on the screen. |
|- | |- | ||
− | | 06 | + | | 06:12 |
| Let us understand the code now. | | Let us understand the code now. | ||
|- | |- | ||
− | |06 | + | |06:15 |
− | |''' keys''' function on | + | |'''keys()''' function on hash returns an array which contains all '''keys''' of '''hash.''' |
|- | |- | ||
− | | 06 | + | | 06:22 |
− | | | + | | '''values()''' function on hash returns an array of values for all '''keys''' of hash. |
|- | |- | ||
− | | 06 | + | | 06:30 |
− | | ''' each''' function returns the ''' key/value''' pair. | + | | '''each()''' function returns the ''' key/value''' pair. |
|- | |- | ||
− | |06 | + | |06:34 |
− | |Here, we have used the ''' while | + | |Here, we have used the '''while''' loop. |
|- | |- | ||
− | | 06 | + | | 06:36 |
− | |It will iterate over each ''' key/value''' pair of | + | |It will iterate over each '''key/value''' pair of hash that is returned by '''each''' function. |
|- | |- | ||
− | |06 | + | |06:43 |
− | | Press ''' Ctrl+S''' to save the file. | + | | Press '''Ctrl+S''' to '''save''' the file. |
|- | |- | ||
− | |06 | + | |06:48 |
|Now, let us execute the script on the terminal by typing | |Now, let us execute the script on the terminal by typing | ||
|- | |- | ||
− | | 06 | + | | 06:53 |
− | | ''' perl perlHash dot pl''' | + | | ''''perl perlHash dot pl'''' |
|- | |- | ||
− | | 06 | + | | 06:58 |
− | | | + | | and press '''Enter'''. |
|- | |- | ||
− | | 07 | + | | 07:01 |
| The following output will be seen on the terminal. | | The following output will be seen on the terminal. | ||
|- | |- | ||
− | | 07 | + | | 07:05 |
− | |Now let us see few other ways of looping over | + | |Now, let us see few other ways of looping over hash. |
|- | |- | ||
− | |07 | + | |07:10 |
− | | We can use ''' foreach | + | | We can use '''foreach''' loop to iterate over each '''key''' of hash. |
|- | |- | ||
− | |07 | + | |07:15 |
− | |Then perform a set of actions on the value of | + | |Then perform a set of actions on the value of key. |
|- | |- | ||
− | |07 | + | |07:20 |
|The syntax is as displayed on the screen. | |The syntax is as displayed on the screen. | ||
|- | |- | ||
− | |07 | + | |07:24 |
− | | Here, each iteration of ''' foreach | + | | Here, each iteration of '''foreach''' loop will assign '''key''' from hash to ''' $variable.''' |
|- | |- | ||
− | |07 | + | |07:32 |
− | |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. |
|- | |- | ||
− | |07 | + | |07:40 |
| Similarly, we can loop over '''hash values''' as shown on the screen. | | Similarly, we can loop over '''hash values''' as shown on the screen. | ||
|- | |- | ||
− | |07 | + | |07:47 |
|We will look at sample program. | |We will look at sample program. | ||
|- | |- | ||
− | |07 | + | |07:49 |
− | |So, let me switch to ''' loopingOverHash dot pl''' in '''gedit.''' | + | |So, let me switch to '''loopingOverHash dot pl''' in '''gedit.''' |
|- | |- | ||
− | |07 | + | |07:55 |
− | | 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'''. |
|- | |- | ||
− | |08 | + | |08:02 |
− | |This piece of code returns single ''' key''' of | + | |This piece of code returns single '''key''' of hash. |
|- | |- | ||
− | |08 | + | |08:07 |
− | |Here in our case, | + | |Here, in our case, |
|- | |- | ||
− | |08 | + | |08:09 |
− | |1st time ''' dollar key ($key)''' contains the ''' Department''' as ''' key.''' | + | |1st time '''dollar key ($key)''' contains the '''Department''' as ''' key.''' |
|- | |- | ||
− | |08 | + | |08:15 |
− | |In the next iteration of '''foreach, Name | + | |In the next iteration of '''foreach''', '''Name''' key is returned. |
|- | |- | ||
− | |08 | + | |08:21 |
− | |Note: ''' Hash''' is an unordered collection of data. | + | |Note: '''Hash''' is an unordered collection of data. |
|- | |- | ||
− | |08 | + | |08:26 |
− | |So, ''' keys''' returned will not be in the sequence defined at the time of creating | + | |So, '''keys''' returned will not be in the sequence defined at the time of creating hash. |
|- | |- | ||
− | |08 | + | |08:33 |
− | | The loop on ''' values''' works in a similar way. | + | | The '''loop''' on '''values''' works in a similar way. |
|- | |- | ||
− | |08 | + | |08:38 |
− | |Press ''' Ctrl + S''' to save the file. | + | |Press '''Ctrl + S''' to '''save''' the file. |
|- | |- | ||
− | |08 | + | |08:41 |
− | |Then, switch to terminal and execute the ''' Perl script''' as | + | |Then, switch to terminal and execute the ''' Perl script''' as: |
|- | |- | ||
− | |08 | + | |08:46 |
|''' perl loopingOverHash dot pl''' | |''' perl loopingOverHash dot pl''' | ||
|- | |- | ||
− | |08 | + | |08:50 |
− | |and press ''' Enter.''' | + | |and press '''Enter.''' |
|- | |- | ||
− | |08 | + | |08:53 |
|The following output is displayed on the terminal. | |The following output is displayed on the terminal. | ||
|- | |- | ||
− | |08 | + | |08:58 |
− | |Let us summarize. | + | |Let us summarize. In this tutorial, we learnt: |
|- | |- | ||
− | | | + | |09:01 |
− | | | + | |'''Hash''' in PERL and |
|- | |- | ||
− | |09 | + | |09:03 |
− | |''' | + | |accessing elements of a '''hash''' |
|- | |- | ||
− | |09 | + | |09:05 |
− | + | ||
− | + | ||
− | + | ||
− | + | ||
|using sample programs. | |using sample programs. | ||
|- | |- | ||
− | |09 | + | |09:08 |
− | |Here is assignment for you | + | |Here is an assignment for you: |
|- | |- | ||
− | |09 | + | |09:11 |
|Declare '''hash''' having '''student name''' as''' key''' | |Declare '''hash''' having '''student name''' as''' key''' | ||
|- | |- | ||
− | |09 | + | |09:15 |
− | | | + | |and his/her percentage as the '''value'''. |
|- | |- | ||
− | |09 | + | |09:18 |
− | |Loop over '''hash''' using '''keys, values''' and '''each''' function | + | |Loop over '''hash''' using '''keys(), values()''' and '''each()''' function. |
|- | |- | ||
− | |09 | + | |09:24 |
− | |Then print the | + | |Then print the percentage of each student. |
|- | |- | ||
− | |09 | + | |09:29 |
− | |Watch the video available at the following link | + | |Watch the video available at the following link. |
|- | |- | ||
− | |09 | + | |09:32 |
− | |It | + | |It summarizes the Spoken Tutorial project. |
|- | |- | ||
− | |09 | + | |09:37 |
− | |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. |
|- | |- | ||
− | | 09 | + | | 09:42 |
− | | The Spoken Tutorial Project | + | | The Spoken Tutorial Project team: Conducts workshops using spoken tutorials. |
|- | |- | ||
− | |09 | + | |09:49 |
− | |Gives certificates to those who pass an online | + | |Gives certificates to those who pass an online test. |
|- | |- | ||
− | |09 | + | |09:53 |
− | |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. |
|- | |- | ||
− | | 10 | + | | 10:02 |
− | | Spoken Tutorial | + | | '''Spoken Tutorial''' project is a part of the "Talk to a Teacher" project. |
|- | |- | ||
− | |10 | + | |10:06 |
|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. | ||
|- | |- | ||
− | |10 | + | |10:15 |
− | |More information on this | + | |More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro. |
|- | |- | ||
− | | 10 | + | | 10:26 |
− | | | + | | Hope you enjoyed this '''PERL''' tutorial. |
|- | |- | ||
− | |10 | + | |10:30 |
− | |This is Amol signing off. | + | |This is Amol, signing off. |
|- | |- | ||
− | |10 | + | |10:33 |
|Thanks for joining. | |Thanks for joining. | ||
|} | |} |
Latest revision as of 15:49, 10 March 2017
Time | Narration |
00:01 | Welcome to the spoken tutorial on Hash in PERL. |
00:05 | In this tutorial, we will learn about: |
00:09 | Hash in PERL and |
00:11 | accessing an element of a hash. |
00:14 | For this tutorial, I am using: |
00:16 | Ubuntu Linux 12.04 operating system |
00:21 | Perl 5.14.2 and |
00:24 | gedit Text Editor. |
00:26 | You can use any text editor of your choice. |
00:30 | To practice this tutorial, you should have knowledge of variables & data Structures in PERL. |
00:38 | Knowledge of comments, loops, conditional statements and arrays will be an added advantage. |
00:46 | Please go through the relevant spoken tutorials on the Spoken Tutorial website. |
00:52 | Hash is an unordered collection of data. |
00:56 | It's a key/value pair data structure. |
00:59 | Hash keys are unique. |
01:01 | However, Hash can have duplicate values. |
01:05 | This is the declaration of a hash. |
01:08 | Let us see how to get the value of a key from hash. |
01:12 | The syntax for accessing the value of a key is: |
01:17 | dollar hashName open curly bracket single quote keyName single quote close curly bracket. |
01:26 | Let us understand hash using a sample program. |
01:31 | I have already typed the code in perlHash dot pl file in gedit. |
01:37 | Type the code as shown in your perlHash dot pl file. |
01:42 | Hash in PERL is declared with percentage sign (%). |
01:47 | These are the keys of hash |
01:49 | and these are the values of hash. |
01:53 | Note: To access key of a hash, one has to use dollar sign. |
01:59 | Press Ctrl + S to save the file. |
02:02 | Then switch to terminal and execute the Perl script as: |
02:08 | perl perlHash dot pl |
02:11 | and press Enter. |
02:14 | The output is as shown on the terminal. |
02:19 | Now, let us see add and delete of keys from hash. |
02:24 | The syntax for: |
02:26 | Adding key is- dollar hashName open curly bracket |
02:30 | single quote KeyName single quote |
02:34 | close curly bracket equal to $value semicolon. |
02:40 | Deleting key is- delete dollar hashName open curly bracket |
02:46 | single quote KeyName single quote close curly bracket semicolon. |
02:53 | Now, let us understand this using a sample program. |
02:58 | I have already typed the code in hashKeyOperations dot pl file. |
03:05 | This is the declaration of a hash. |
03:08 | We will be adding, deleting the keys from this hash. |
03:13 | Here we are adding a key to an already created hash. |
03:18 | It is like assigning a value to a variable. |
03:23 | delete keyword is used to delete the key. |
03:27 | We need to pass the key to delete it. |
03:31 | Press Ctrl+S to save the file. |
03:35 | Switch to the terminal and execute the Perl script as: |
03:40 | perl hashKeyOperations dot pl |
03:44 | and press Enter. |
03:47 | Output will be as shown on the terminal. |
03:52 | Let us look at sorting of hash keys and values. |
03:57 | Syntax to sort keys is: |
04:00 | sort open bracket keys percentage hashName close bracket semicolon. |
04:07 | Similarly, we can sort hash values as: |
04:11 | sort open bracket values percentage hashName close bracket semicolon. |
04:18 | Let us understand sorting functionality using a sample program. |
04:24 | Let me switch to sortHash dot pl on gedit. |
04:30 | Type the code as displayed on the screen, in your sortHash dot pl file. |
04:36 | Here, we have declared hash of address. |
04:41 | Here, to sort the keys, we have used the sort inbuilt function along with the keys function. |
04:49 | This will sort the hash keys in alphabetical order. |
04:54 | Similarly, we can use the sort function on values of hash. |
04:59 | Sorting can also be done on numeric keys and/or values. |
05:05 | Save the file and switch to terminal. |
05:09 | Execute the script by typing perl sortHash dot pl and press Enter. |
05:17 | The output will be as shown on the terminal. |
05:22 | Now, let us see how to get all keys and values of a hash. |
05:27 | PERL provides inbuilt function to fetch all the hash keys and values. |
05:34 | keys() function is used to retrieve all the keys of a hash, |
05:40 | values() function returns values of all the keys whereas |
05:46 | each() function iterates over hash and returns key/value pair from hash. |
05:53 | Let us understand these using a sample program. |
05:57 | For this, we'll use perlHash dot pl script which we have created earlier in this tutorial. |
06:07 | Type the following piece of code as shown on the screen. |
06:12 | Let us understand the code now. |
06:15 | keys() function on hash returns an array which contains all keys of hash. |
06:22 | values() function on hash returns an array of values for all keys of hash. |
06:30 | each() function returns the key/value pair. |
06:34 | Here, we have used the while loop. |
06:36 | It will iterate over each key/value pair of hash that is returned by each function. |
06:43 | Press Ctrl+S to save the file. |
06:48 | Now, let us execute the script on the terminal by typing |
06:53 | 'perl perlHash dot pl' |
06:58 | and press Enter. |
07:01 | The following output will be seen on the terminal. |
07:05 | Now, let us see few other ways of looping over hash. |
07:10 | We can use foreach loop to iterate over each key of hash. |
07:15 | Then perform a set of actions on the value of key. |
07:20 | The syntax is as displayed on the screen. |
07:24 | Here, each iteration of foreach loop will assign key from hash to $variable. |
07:32 | Then, it will use that $variable to fetch the value or to perform a set of actions. |
07:40 | Similarly, we can loop over hash values as shown on the screen. |
07:47 | We will look at sample program. |
07:49 | So, let me switch to loopingOverHash dot pl in gedit. |
07:55 | Type the following piece of code as shown in your loopingOverHash dot pl. |
08:02 | This piece of code returns single key of hash. |
08:07 | Here, in our case, |
08:09 | 1st time dollar key ($key) contains the Department as key. |
08:15 | In the next iteration of foreach, Name key is returned. |
08:21 | Note: Hash is an unordered collection of data. |
08:26 | So, keys returned will not be in the sequence defined at the time of creating hash. |
08:33 | The loop on values works in a similar way. |
08:38 | Press Ctrl + S to save the file. |
08:41 | Then, switch to terminal and execute the Perl script as: |
08:46 | perl loopingOverHash dot pl |
08:50 | and press Enter. |
08:53 | The following output is displayed on the terminal. |
08:58 | Let us summarize. In this tutorial, we learnt: |
09:01 | Hash in PERL and |
09:03 | accessing elements of a hash |
09:05 | using sample programs. |
09:08 | Here is an assignment for you: |
09:11 | Declare hash having student name as key |
09:15 | and his/her percentage as the value. |
09:18 | Loop over hash using keys(), values() and each() function. |
09:24 | Then print the percentage of each student. |
09:29 | Watch the video available at the following link. |
09:32 | It summarizes the Spoken Tutorial project. |
09:37 | If you do not have good bandwidth, you can download and watch it. |
09:42 | The Spoken Tutorial Project team: Conducts workshops using spoken tutorials. |
09:49 | Gives certificates to those who pass an online test. |
09:53 | For more details, please write to: contact at spoken hyphen tutorial dot org. |
10:02 | Spoken Tutorial project is a part of the "Talk to a Teacher" project. |
10:06 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
10:15 | More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro. |
10:26 | Hope you enjoyed this PERL tutorial. |
10:30 | This is Amol, signing off. |
10:33 | Thanks for joining. |