Difference between revisions of "PERL/C2/Data-Structures/English"

I will also be using the gedit Text Editor.

You can use any text editor of your choice.

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

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

1. Scalar
2. Array
3. Hash, also, called as Associative Array

1. This type of data structure holds a value of any data type.
2. The data type can be string, number, double etc.
3. It can also hold the reference to an array or reference to a hash.

Note: Reference in Perl will be covered in subsequent tutorial.

Declaring scalar data structure;

$count = 12;

$string = 'I am scalar of type string';

$count = 12;

$string = 'I am scalar of type string';

1. Assign a value to it
2. Assign one scalar to another
3. Arithmetic operations on number type of scalars like add, subtract etc
4. string operations on string scalar like concatenation, substr etc

Type gedit scalars dot pl & >> Press Enter.

#!/usr/bin/perl

# Following are the various ways of declaring sclar

$count = 12;

$string = 'I am scalar of type string';

=head

Few of the arithmatic operations that

can be performed on the sclars

=cut

$newCount = $count;

print "Original Count: $newCount\n";

$newCount = $newCount + 12; #Can be written as $newCount += 12;

print "New Count After Addition: $newCount\n";

$newCount = $newCount - 12; #Can be written as $newCount -= 12;

print "New Count After Substraction: $newCount\n";

=head

Few of the string operations that

can be performed on the sclars

=cut

$string = $string. ' in Perl'; #can be written as $string .= ' in Perl';

print "Original String: $string\n";

$newString = substr($string, 0, 11);

print "New String: $newString\n";

Type the code as displayed on the screen.

This is the declaration and assignment to the scalar.

These are few arithmetic operations that can be performed on number type of scalar

<pause>

These are string operations that can be performed on string type of scalar.

<pause>

substr is the PERL function which provides part of the string as output.

Here index 0 specifies start of a string, i.e. from where we want to start extraction of the string.

And 11 is the offset upto where we want the string to be in the output.

perl scalars.pl

perl scalars dot pl and press Enter.

Original Count: 12

New Count After Addition: 24

New Count After Substraction: 12

String: I am scalar of type string in Perl

New String: I am scalar

Original Count: 12

New Count After Addition: 24

New Count After Substraction: 12

String: I am scalar of type string in Perl

New String: I am scalar

1. It is a list of elements.
2. Elements can be string, number etc.
3. It has an index, which is used for performing various operations on the array.
4. Index starts with zero.
5. Unlike other programming languages, there is no need to declare an array or its length before using it in Perl.
6. Perl array, stretches or shrinks as per the elements added or removed from it

Highlight @variableName = (element 1, element 2, ..., element N);

at the rate variable name space equal to space open bracket list of elements separated with comma close bracket semicolon

#!/usr/bin/perl

#Number array

@numArray = (98, 99, 92, 97);

#String array

@strArray = ('Perl', 'String', 'Array');

#Mix array

@array = (98, 'StringValue', 92);

Type the following code as displayed on the screen.

This is the number array which has elements of number type.

This is the string array which has elements of string type.

This array has elements of both number and string type.

Highlight all 3 types of array

print “Number Array: @numArray\n”;

print “String Array: @strArray\n”;

print “Array: @array\n”;

Now let us see how to print the array.

Type

print space double quote Number Array colon space at the rate numArray slash n double quote semicolon

Press Enter

Similarly, print other 2 arrays as

print “String Array: @strArray\n”;

print “Array: @array\n”;

perl perlArray dot pl and press Enter.

Number Array: 98 99 92 97

String Array: Perl String Array

Array: 98 StringValue 92

Number Array: 98 99 92 97

String Array: Perl String Array

Array: 98 StringValue 92

1. Hash is alternatively called as Associative array.
2. It is a Key Value pair data structure.
3. Key in hash is unique.
4. If the same key is added again, then the value of that key will be overridden by the latest value assigned to the key.
5. Value can be duplicate.
6. It also holds value of any data type.

Highlight

%variableName = (

'Key1' => 'Value1' ,

'Key2' => 'Value2'

);

percentage variable name space equal to space open bracket

Press Enter

single quote key Name single quote space equal to greater than sign space Value comma

Press Enter

single quote key Name single quote space equal to greater than sign space Value

Press Enter

close bracket semicolon

gedit perlHash dot pl & and press Enter.

#!/usr/bin/perl

use Data::Dumper;

#Hash of marks obtain in a subject

%hash = (

'Subject' => 'Math',

'Marks' => 98

);

Type the following code as displayed on the screen.

This hash indicates the marks obtained in a subject.

Highlight

print "Hash: ", Dumper \%hash;

Now let us see how to print the hash.

For now, just note the way I have printed the hash.

Detailed explanation will be given in a subsequent tutorial.

perl perlHash.pl

perl perlHash dot pl and press Enter.

Hash:

$VAR1 = {

'Subject' => 'Math',

'Marks' => 98

};

Hash:

$VAR1 = {

'Subject' => 'Math',

'Marks' => 98

};

In this tutorial, we have learnt -

• scalar
• Array and
• Hash Data Structure in Perl
• using sample programs.

1. Declare scalar variable
2. Assign value of type float to it and then print it.
3. Declare and print an array of colors 'Red', 'Yellow' and 'Green'.
4. Declare and print a hash of Employee Name and their department.

Hint:

'Employee' => 'John',

'Department' => 'Engineering'

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