Difference between revisions of "PERL/C2/Array-functions/English-timed"

|Welcome to the spoken tutorial on '''Array Functions''' in '''Perl'''

| In this tutorial, we will learn about '''Array functions''' in '''Perl''', like  

|'''push '''

| '''pop'''  

|'''shift'''

| '''unshift '''

 

|'''split'''

| '''splice '''

 

| and ''' join'''

| '''sort'''

 

| '''qw'''

|I am using ''' Ubuntu Linux12.04''' operating system and '''Perl 5.14.2'''

|You should have basic knowledge of ''' Variables,  Data Structures'''  and '''Arrays''' in '''Perl'''

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

|These '''functions''' can perform various operations on an '''Array. '''

| Let us first learn how to add and remove elements from last position of an '''Array'''.  

|'This can be done by using;

| '''push function''' which adds an element at the last position of an '''Array'''  

|and ''' pop function''' which removes an element from the last position of an '''Array'''  

| Let us understand '''push''' and '''pop functions''' by using a sample program.  

|Open the terminal and type ''' gedit perlArray dot pl space ampersand '''

| And Press ''' Enter '''

|This will open ''' perlArray dot pl''' file in '''gedit'''.

|Type the code as shown on the screen  

| Here, we have declared an '''Array''' of length 3.  

| '''push function''' will insert an element at the last position of this '''Array''' i.e after 3;

|whereas, ''' pop function''' will remove an element from the last position of the '''Array'''.  

|In our case, 4 will be removed from the '''Array'''.  

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

|'''push function''' takes 2 '''arguments'''-  

|'''1st argument''' to the '''push function''', is the '''Array''' in which to add an '''element'''.  

|''' 2nd argument'''  is the '''element''' which is to be '''pushed''' into the '''Array'''.  

| The syntax of ''' pop function''' is as follows -

|''' pop function''' takes only one '''argument '''

|It is the '''Array''' from which an '''element''' needs to be removed.  

|Note: Both these functions work at ''' last position''' of an '''Array'''.  

|The '''element''' removed by ''' pop function''' can be collected into another '''variable'''.

|The syntax for this is ''' $variable space = space pop open bracket @myArray close bracket '''

|Type '''perl perlArray dot pl''' and press '''Enter.'''

| Now, let us see how to add/remove an '''element''' from the ''' 1st position''' of an ''' Array'''.

|''' unshift function''' - which adds an '''element''' to an '''Array''' at the 1st position  

|''' shift function''' - which removes the first '''element''' from an '''Array'''.  

|I will open ''' perlArray dot pl''' file which I have already created.  

| ''' unshift''' function will insert an '''element''' at the first position i.e before 1  

| '''shift''' function will remove an ''' element''' from the first position.  

| In our case, ''' zero''' will be removed.  

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

|The ''' unshift function''' takes 2  '''arguments '''-  

|'''1st argument''' is the '''Array''' in which to add an '''element'''  

|''' 2nd argument''' is the '''element''' to be added into the '''Array '''

|''' shift function''' takes only one '''argument''' -  

|This is the '''Array''' from which the '''element ''' needs to be removed.  

| ''' Note:''' Both these functions works at '''first position''' of an '''Array'''.  

| We can collect the '''element''' removed by '''shift function''' into some variable.  

|This syntax for this is ''' - $variable space =  space shift open bracket @myArray close bracket '''

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

|Type ''' perl perlArray dot pl''' and press '''Enter'''.

|Now, let us see how to remove an ''' element''' from a specified position of an '''Array.'''  

|''' splice function''' removes an ''' element''' from a specified position of an '''Array'''.  

|The ''' return value''' of this '''function''' is an ''' Array''' of removed elements.  

|Go to the ''' perlArray dot pl ''' file, which we created earlier.  

| We need to provide ''' index'''  from where we want to remove the ''' elements''' and  

| the ''' offset''' upto which we want to remove the '''elements '''

| In our case, the '''elements''' 5 and 6 will be removed.  

| Then switch to the ''' terminal'''  and execute the ''' Perl script''' by typing -

| ''' perl perlArray dot pl''' and press '''Enter.'''

|The output is as shown on the terminal

| Now let us look at few other ''' inbuilt functions''' of '''Arrays.'''

| ''' split function''' is used to divide a '''string''' at a specified '''delimiter. '''

|The return value of this ''' function''' is an '''Array'''.  

|The ''' elements''' of this '''Array''' are the divided portions of the '''string.'''  

| ''' join function''' joins the '''elements''' of an '''Array''' , using the specified '''delimiter. '''

|It returns a string of joined '''elements.'''  

| ''' sort function''' sorts an '''Array''' in alphabetical/numerical order.  

| ''' qw function ''' returns an '''Array''' of words, separated by a '''white space'''.

| Now let us understand all these ''' functions''' using a sample program.  

|Switch to ''' terminal''' and type  

| ''' gedit arrayFunctions dot pl space ampersand and Press Enter'''

|In this case, each word of the ''' variable string''' will become an ''' element''' of an '''Array'''

|''' sort function''' will sort the '''elements''' of  an '''Array''' in alphabetical order.  

| '''qw function''' creates an '''Array''' of words separated by space.

| Let us understand each '''function.'''

|'''split function''' takes two '''arguments'''.

|''' 1st argument''' is the ''' delimiter''' by which the ''' string''' needs to be split  

|''' 2nd''' is the '''string''' which needs to be split.  

|'''Delimiters''' can be specified in ''' forward slash, single or double quotes. '''

|''' join function''' takes 2 '''arguments'''.

|1st is the '''delimiter''' by which the '''Array elements''' needs to be joined.   

|2nd is the '''Array.'''  

|'''Delimiters'''  can be specified in '''single or double quotes. '''

| ''' sort function''' takes a single '''argument''' , which is the '''Array''' that needs to be sorted.  

|''' qw function''' returns an ''' Array''' of words, separated by ''' space.'''

|It is not necessary to specify the word in ''' quotes''' , if written using '''qw. '''

|Then switch to the terminal and execute the ''' Perl script''' by typing -

|''' perl arrayFunctions dot pl'''

|Let us summarize.  

 

|In this tutorial, we have learnt to -

|add/remove ''' elements'''  from an '''Array '''

|basic functions which can be performed on '''Array''' using sample programs

|Here is assignment for you -   

|split the above ''' string at '/ ' ''' (forward slash) '''delimiter '''

|Add ''' https:// ''' at the start of an newly created '''Array'''   

|Remove ''' element “Perl” ''' from the '''Array '''

|Declare number '''Array ''' and sort it  

|Watch the video available at the following link

|It summaries the Spoken Tutorial project

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

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| Hope you enjoyed this Perl tutorial.  

|This is Amol signing off.