Difference between revisions of "PERL/C2/Arrays/English-timed"

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

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

|-

|-

| In this tutorial, we will learn about  

| In this tutorial, we will learn about  

|-

|-

|'''Index''' of an '''array'''  

|'''Index''' of an '''array'''  

   

   

|-

|-

| Length of an '''array '''

| Length of an '''array '''

   

   

|-

|-

|Accessing '''elements''' of an '''array'''  

|Accessing '''elements''' of an '''array'''  

   

   

|-

|-

| Looping over an '''array '''

| Looping over an '''array '''

|-

|-

|'''Sequential Array'''  

|'''Sequential Array'''  

|-

|-

| And '''Array Slicing '''

| And '''Array Slicing '''

|-

|-

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

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

   

   

|-

|-

|I will also be using the '''gedit''' Text Editor.  

|I will also be using the '''gedit''' Text Editor.  

   

   

|-

|-

| You can use any text editor of your choice.  

| You can use any text editor of your choice.  

   

   

|-

|-

|You should have basic knowledge of ''' Variables, Comments & Data Structures''' in '''Perl'''

|You should have basic knowledge of ''' Variables, Comments & Data Structures''' in '''Perl'''

|-

|-

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

|Knowledge of ''' loops and conditional statements''' 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.  

|-

|-

|'''Array''' is a simple '''data structure''' which contains '''elements''' of any '''data type'''.   

|'''Array''' is a simple '''data structure''' which contains '''elements''' of any '''data type'''.   

|-

|-

|'''Array index''' starts from zero always.  

|'''Array index''' starts from zero always.  

|-

|-

| In '''Perl''', it is not necessary to declare the length of an '''array'''.   

| In '''Perl''', it is not necessary to declare the length of an '''array'''.   

|-

|-

|'''Array'''  length expands/shrinks as and when elements are added/removed from it.  

|'''Array'''  length expands/shrinks as and when elements are added/removed from it.  

|-

|-

| The syntax for declaring an array is -  

| The syntax for declaring an array is -  

   

   

|-

|-

|'''@myArray equal to open bracket 1 comma  2 comma 3 comma  single quote abc single quote  comma 10.3 close  bracket semicolon'''

|'''@myArray equal to open bracket 1 comma  2 comma 3 comma  single quote abc single quote  comma 10.3 close  bracket semicolon'''

|-

|-

|The last index of an array can be found with this command -  

|The last index of an array can be found with this command -  

   

   

|-

|-

|'''$#myArray '''

|'''$#myArray '''

   

   

|-

|-

| Let us understand this using sample program.  

| Let us understand this using sample program.  

   

   

|-

|-

|Open the terminal and type  

|Open the terminal and type  

|-

|-

|'''gedit arrayIndex dot pl space ampersand '''

|'''gedit arrayIndex dot pl space ampersand '''

   

   

|-

|-

| and press '''Enter. '''

| and press '''Enter. '''

|-

|-

| This will open '''arrayIndex dot pl''' file in '''geditor'''

| This will open '''arrayIndex dot pl''' file in '''geditor'''

   

   

|-

|-

|Type the piece of code that is displayed on screen   

|Type the piece of code that is displayed on screen   

    

    

|-

|-

|Here we have declared & defined an '''array''' which contains 5 elements.  

|Here we have declared & defined an '''array''' which contains 5 elements.  

   

   

|-

|-

|As array index starts from zero, the last index value will be 4  

|As array index starts from zero, the last index value will be 4  

   

   

|-

|-

|i.e number of elements, which is 5, minus 1.  

|i.e number of elements, which is 5, minus 1.  

   

   

|-

|-

|Press Ctrl+S to save the file.  

|Press Ctrl+S to save the file.  

|-

|-

|Now switch to  terminal and execute the Perl script

|Now switch to  terminal and execute the Perl script

|-

|-

| Type ''' perl arrayIndex dot pl '''

| Type ''' perl arrayIndex dot pl '''

|-

|-

|and press '''Enter.'''

|and press '''Enter.'''

   

   

|-

|-

|The output will be as displayed on the terminal  

|The output will be as displayed on the terminal  

   

   

|-

|-

|Now, let us see how to get length of an array in Perl.  

|Now, let us see how to get length of an array in Perl.  

   

   

|-

|-

|There are many ways by which we can find the length of an array.  

|There are many ways by which we can find the length of an array.  

|-

|-

|Index of an '''array + 1  i.e. $#array + 1 '''

|Index of an '''array + 1  i.e. $#array + 1 '''

   

   

|-

|-

|Using PERL inbuilt '''scalar function; i.e.  '''scalar''' open bracket '''@array''' close bracket  

|Using PERL inbuilt '''scalar function; i.e.  '''scalar''' open bracket '''@array''' close bracket  

   

   

|-

|-

|Assign array to a ''' scalar variable i.e. $arrayLength = @array '''

|Assign array to a ''' scalar variable i.e. $arrayLength = @array '''

   

   

|-

|-

| Let us look at an illustration of array length using a sample program.   

| Let us look at an illustration of array length using a sample program.   

   

   

|-

|-

| Switch to the terminal and type -   

| Switch to the terminal and type -   

|-

|-

| '''gedit arrayLength dot pl space ampersand '''

| '''gedit arrayLength dot pl space ampersand '''

   

   

|-

|-

|Press '''Enter.'''

|Press '''Enter.'''

   

   

|-

|-

|  Type the following piece of code, as shown on the screen-  

|  Type the following piece of code, as shown on the screen-  

   

   

|-

|-

|Here we have declared & defined an array which contains 5 elements.  

|Here we have declared & defined an array which contains 5 elements.  

   

   

|-

|-

|So, output will display 5.  

|So, output will display 5.  

   

   

|-

|-

|Highlighted, are various ways to find the length of an array in Perl.  

|Highlighted, are various ways to find the length of an array in Perl.  

   

   

|-

|-

| Please note We have '''concatenated''' the output in the print statement using comma.  

| Please note We have '''concatenated''' the output in the print statement using comma.  

   

   

|-

|-

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

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

    

    

|-

|-

| Now let us execute the script.  

| Now let us execute the script.  

   

   

|-

|-

|  Switch to terminal and type-  

|  Switch to terminal and type-  

|-

|-

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

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

   

   

|-

|-

| The output will be as displayed on the terminal.

| The output will be as displayed on the terminal.

|-

|-

| Now, let us understand how to access individual elements in an array.  

| Now, let us understand how to access individual elements in an array.  

|-

|-

|'''Indexing''' is used to access elements of an array.  

|'''Indexing''' is used to access elements of an array.  

   

   

|-

|-

|Let us look at an example for accessing elements of an array at -  

|Let us look at an example for accessing elements of an array at -  

   

   

|-

|-

|First Position  

|First Position  

|-

|-

|Last Position  

|Last Position  

|-

|-

|Any position  

|Any position  

   

   

|-

|-

| Switch to the terminal and type -  

| Switch to the terminal and type -  

|-

|-

| '''gedit perlArray dot pl space ampersand '''

| '''gedit perlArray dot pl space ampersand '''

   

   

|-

|-

|and press '''Enter.'''  

|and press '''Enter.'''  

   

   

|-

|-

|Type the following piece of code as shown.  

|Type the following piece of code as shown.  

   

   

|-

|-

|Please note-  

|Please note-  

   

   

|-

|-

|'''myArray''' is declared with '''@''' (at the rate) sign.  

|'''myArray''' is declared with '''@''' (at the rate) sign.  

   

   

|-

|-

|But, to access an array element we need to use ''' $ (dollar)''' sign.  

|But, to access an array element we need to use ''' $ (dollar)''' sign.  

|-

|-

|To access the element at any position, we need to pass '''index''' to an array  

|To access the element at any position, we need to pass '''index''' to an array  

|-

|-

|Here, to access the first element of '''myArray''' ,  

|Here, to access the first element of '''myArray''' ,  

|-

|-

|zero is passed as '''index. '''

|zero is passed as '''index. '''

|-

|-

|To access the last element of '''myArray''' , we have passed the last '''index''' of '''myArray.'''

|To access the last element of '''myArray''' , we have passed the last '''index''' of '''myArray.'''

   

   

|-

|-

| Recall, we had learnt about this earlier.  

| Recall, we had learnt about this earlier.  

   

   

|-

|-

| Press Ctrl + S to save the file.  

| Press Ctrl + S to save the file.  

|-

|-

| Switch to the terminal and execute the  script as -

| Switch to the terminal and execute the  script as -

|-

|-

| '''perl perlArray dot pl'''

| '''perl perlArray dot pl'''

   

   

|-

|-

| and press '''Enter.'''

| and press '''Enter.'''

|-

|-

| The output will be as shown on the terminal  

| The output will be as shown on the terminal  

|-

|-

| Now, let us understand, how to '''loop over'''  each element of an array.

| Now, let us understand, how to '''loop over'''  each element of an array.

|-

|-

|There are two ways of '''looping over''' an array-

|There are two ways of '''looping over''' an array-

   

   

|-

|-

|  Using '''for loop '''

|  Using '''for loop '''

    

    

|-

|-

| Using '''foreach loop '''

| Using '''foreach loop '''

|-

|-

|Let's learn how to use these loops to iterate over an array using a sample program.  

|Let's learn how to use these loops to iterate over an array using a sample program.  

|-

|-

|For this, switch to the terminal and type   

|For this, switch to the terminal and type   

|-

|-

| '''gedit loopingOverArray dot pl space ampersand '''

| '''gedit loopingOverArray dot pl space ampersand '''

|-

|-

|And Press '''Enter'''

|And Press '''Enter'''

   

   

|-

|-

| Type the piece of code as shown on the screen  

| Type the piece of code as shown on the screen  

|-

|-

| Here, we are printing each element of  array by iterating the index.  

| Here, we are printing each element of  array by iterating the index.  

|-

|-

| The '''for loop''' will execute till the value of i variable reaches the last '''index''' of an array.  

| The '''for loop''' will execute till the value of i variable reaches the last '''index''' of an array.  

   

   

|-

|-

|Here, '''foreach loop''' will be executed for each element of an array.

|Here, '''foreach loop''' will be executed for each element of an array.

   

   

|-

|-

| Once the array reaches its last element, it will exit the ''' foreach''' loop.  

| Once the array reaches its last element, it will exit the ''' foreach''' loop.  

   

   

|-

|-

|Please Note: If you are not aware of '''for''' and '''foreach''' loops,  

|Please Note: If you are not aware of '''for''' and '''foreach''' loops,  

   

   

|-

|-

|please go through the relevant spoken tutorials on  spoken tutorial website.  

|please go through the relevant spoken tutorials on  spoken tutorial website.  

 

 

|-

|-

| Now, Press Ctrl + S to save the file.  

| Now, Press Ctrl + S to save the file.  

|-

|-

|Then switch to the terminal and execute the script as -

|Then switch to the terminal and execute the script as -

|-

|-

| '''perl loopingOverArray dot pl'''

| '''perl loopingOverArray dot pl'''

|-

|-

| and press '''Enter.'''

| and press '''Enter.'''

   

   

|-

|-

|The output will be as displayed on the terminal.   

|The output will be as displayed on the terminal.   

|-

|-

| In '''Perl''', we can declare a '''sequential array''' as-  

| In '''Perl''', we can declare a '''sequential array''' as-  

|-

|-

|'''@alphaArray''' = open bracket '''a''' dot dot '''d''' close bracket semicolon  

|'''@alphaArray''' = open bracket '''a''' dot dot '''d''' close bracket semicolon  

|-

|-

|i.e '''alphaArray''' will contain elements 'a', 'b', 'c' and 'd'  

|i.e '''alphaArray''' will contain elements 'a', 'b', 'c' and 'd'  

|-

|-

|Similarly, '''@numericArray ''' equal to open bracket 1 dot dot 5 close bracket semicolon  is same as  

|Similarly, '''@numericArray ''' equal to open bracket 1 dot dot 5 close bracket semicolon  is same as  

'''@numericArray'''  equal to  open bracket 1 comma  2 comma 3 comma  4 comma 5  

'''@numericArray'''  equal to  open bracket 1 comma  2 comma 3 comma  4 comma 5  

|-

|-

|Perl also provides array slicing.  

|Perl also provides array slicing.  

|-

|-

|This is nothing but extracting part of an array and dumping it into a new array.  

|This is nothing but extracting part of an array and dumping it into a new array.  

|-

|-

|'''@array = 19  comma 23 comma 56 comma 45 comma 87 comma 89  close bracket semicolon '''

|'''@array = 19  comma 23 comma 56 comma 45 comma 87 comma 89  close bracket semicolon '''

|-

|-

| '''@newArray''' = '''@array ''' open square bracket 1 comma 4 close square bracket semicolon  

| '''@newArray''' = '''@array ''' open square bracket 1 comma 4 close square bracket semicolon  

|-

|-

|After slicing, the  newArray will look like  

|After slicing, the  newArray will look like  

|-

|-

|'''@newArray''' =  open bracket 23 comma 87 close bracket semicolon  

|'''@newArray''' =  open bracket 23 comma 87 close bracket semicolon  

|-

|-

|Let us summarize.  

|Let us summarize.  

|-

|-

|In this tutorial, we have learnt to-  

|In this tutorial, we have learnt to-  

|-

|-

|Find index of an array  

|Find index of an array  

|-

|-

|Find length of an array  

|Find length of an array  

|-

|-

|Access elements of an array  

|Access elements of an array  

|-

|-

|Loop over an array  

|Loop over an array  

|-

|-

|Sequenial Array  

|Sequenial Array  

|-

|-

|Array Slicing using sample programs.  

|Array Slicing using sample programs.  

|-

|-

|Here is assignment for you -  

|Here is assignment for you -  

|-

|-

|Declare an array of rainbow colors  

|Declare an array of rainbow colors  

|-

|-

|Print 4th element of this array  

|Print 4th element of this array  

|-

|-

|Print Length and last index of this array  

|Print Length and last index of this array  

|-

|-

|Loop over each element of an array using for & foreach loops  

|Loop over each element of an array using for & foreach loops  

|-

|-

|Declare array as @myArray = open bracket 1..9 close bracket semicolon and then create an array of odd numbers from above array using array slicing.  

|Declare array as @myArray = open bracket 1..9 close bracket semicolon and then create an array of odd numbers from above array using array slicing.  

|-

|-

|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.

   

   

|}

|}