Perl Data Types

We need not to specify the type of data in Perl. Perl interpreter choose it automatically based on the context of data.

 Perl has three data types: 

 1) Scalars: 
  1. Scalars are single data unit. 
  2. A scalar can be integer, float, string etc. Scalar variables are prefixed with “$” sign.
Perl supports following operators on scalars:

  1. Concatenation of string values via the . (dot) operator.
  2. Math functions on numeric values: + - * / % ^^ as well as a rich set of functions.
  3. Operations on own variable: += -= .= ++ -- etc.
Integer Example: 
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#!/usr/bin/perl
use strict;  
use warnings;  

#scalar data could be integer or float
my $v = -2;
my $w = 2;
my $x = 5;
my $y = 10.50;
my $z = 20;

print "X = $x\n";
print "Y = $y\n";
print "Z = $z\n";
print $x + $y . "\n";
print $y * $z, "\n";
print $x . $w, "\n";

my $p = "5";  
my $q = "2cm";  
print print $p . $q, "\n";
Output:
5
10.5
20
15.5
210
52
52cm

 String Example:
i) Print String Variables

$size=15; 
$name = "Vinod";

print "Hello, $name\n";     # prints Hello, Vinod
print 'Hello, $name\n';     # prints Hello, $name\n
Output:
Hello, Vinod
Hello, $name\n

ii) Print String Variables

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# scalar variable example
$item_name = "Apple";
$item_price = 13.50;
$item_count = 5;
print "The total cost for $item_count $item_name" . "s" . " will be: " . $item_count * $item_price . " Dollars.\n";

# Alternate way
$total = $item_count * $item_price;
$item_name_plural = $item_name . "s";
print "The total cost for $item_count $item_name_plural will be: $total Dollars.\n";
Output: 
The total cost for 5 Apples will be: 67.5 Dollars.
The total cost for 5 Apples will be: 67.5 Dollars.

iii) Alternative delimiters
Besides the single and double-quotes, Perl also allows you to use quote-like operators such as:
a. The  q// acts like single-quoted string.
b. The  qq// acts like double-quoted string. 

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#!/usr/bin/perl
use warnings;
use strict;
 
my $s= q/"Are you learning Perl String today?" We asked./;
print($s ,"\n");
 
my $name = 'Jack';
my $s2 = qq/"Are you learning Perl String today?"$name asked./;
print($s2 ,"\n");
Output:
"Are you learning Perl String today?" We asked.
"Are you learning Perl String today?"Jack asked.

 iv) String functions
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#!/usr/bin/perl
my $s = "This is a sample string";

print("To upper case:\n");
print(uc($s),"\n");
 
print("To lower case:\n");
print(lc($s),"\n");

my $sub = "sample";
my $p = index($s,$sub); # rindex($s,$sub);
print(qq\The substring "$sub" found at position "$p" in string "$s"\,"\n");

Output:
To upper case:
THIS IS A SAMPLE STRING
To lower case:
this is a sample string
The substring "sample" found at position "10" in string "This is a sample string"


 v) This function will get two strings and return the location of the second string within the first string. 
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use strict;
use warnings;
 
my $str = "The black cat climbed the green tree";
 
print "Index of cat: ", index $str, 'cat';
print "\nIndex of dog: ", index $str, 'dog';
print "\nIndex of The: ", index $str, "The";
print "\nIndex of the: ", index $str, "the";
Output:
Index of cat: 10
Index of dog: -1
Index of The: 0
Index of the: 22

 vi)Perl String Escaping Characters 
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use strict;
use warnings;

#Printing E-mail Address
my $site  = "javatpoint\@gmail.com";  
print "$site\n"; #prints javatpoint@gmail.com

#Perl $ sign Embedding in Double quote String
my $msg1 = 'GoodMorning';  
print "We have defined \$msg1 as $msg1\n"; #Prints We have defined $msg1 as GoodMorning

#Escaping Escape Character
print "The \\n is a new line.\n"; #print The \n is a new line.

#Escaping Double quotes
my $x = 'Perl';  
print "This \"blogspot\" is \"$x\" tutorials\n";
Output:
javatpoint@gmail.com
We have defined $msg1 as GoodMorning
The \n is a new line.
This "blogspot" is "Perl" tutorials

 vii) q and qq operator
a. The qq operator replaces double quote surrounding a string by its parentheses. You can use qq instead of ("").
b. The q operator replaces single quote surrounding a string by its parentheses. You can use q instead of ('). 
 
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use strict;
use warnings;

my $str  = "World is beautiful";
print qq(This is sample text\n);
print qq(The value of \$str is \"$str\. \n");

my $str1  = "World is beautiful";
print q(The value of \$str1 is \"$str1\. \n");
Output: 
This is sample text
The value of $str is "World is beautiful.
The value of \$str1 is \"$str1\. \n"

vii)What is chop() and chomp() function in Perl?
  1. Perl chop() function removes last character from a string regardless of what that character is. It returns the chopped character.
  2. Perl chomp() function removes any new line character from end of the string. It returns the number of characters removed from the string.
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#chop() function removes last character from a string   
$a = "AEIOU";    
$b = chop($a);  
print "$a\n";  #it will return AEIO. 
print "$b\n";  #it will return U.    


#chomp() EXAMPLES    
$a = "AEIOU\n";   
$b= chomp($a);    
print "$a $b";  #it will return AEIOU 1
Output:
AEIO
U
AEIOU 1

2) Arrays: 
  1. Arrays are ordered list of scalars
  2. Array variables are prefixed with “@” sign 
Example:
@names = ("Vinod", "Amol", "Yusuf", "Nilesh");
print "\$names[0] = $names[0]\n";
Output: $names[0] = Vinod
3) Hashes: 
  1. Perl hashes are an unordered collection of key-value pairs. 
  2. They are preceded by (%) sign and accessed using keys.
Example: 
%data = ('Vinod', 25, 'Amol', 40, 'Yusuf', 30);
print "\$data{'Vinod'} = $data{'Vinod'}\n";
Output: $data{'Vinod'} = 25


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