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Programming Scripts Articles
Page 19 of 33
Perl Scalar Variables
A scalar is a single unit of data. That data might be an integer number, floating-point, a character, a string, a paragraph, or an entire web page. Simply saying it could be anything, but only a single thing.Here is a simple example of using scalar variables −Example#!/usr/bin/perl $age = 25; # An integer assignment $name = "John Paul"; # A string $salary = 1445.50; # A floating point print "Age = $age"; print "Name = $name"; print "Salary = $salary";OutputThis will produce the following result −Age = 25 Name = John Paul Salary = 1445.5
Read MorePerl Array Variables
An array is a variable that stores an ordered list of scalar values. Array variables are preceded by an "at" (@) sign. To refer to a single element of an array, you will use the dollar sign ($) with the variable name followed by the index of the element in square brackets.Here is a simple example of using array variables −Example#!/usr/bin/perl @ages = (25, 30, 40); @names = ("John Paul", "Lisa", "Kumar"); print "\$ages[0] = $ages[0]"; print "\$ages[1] = $ages[1]"; print "\$ages[2] = $ages[2]"; print "\$names[0] = $names[0]"; print "\$names[1] = $names[1]"; print "\$names[2] = $names[2]";Here we used escape sign ...
Read MorePerl Hash Variables
A hash is a set of key/value pairs. Hash variables are preceded by a percent (%) sign. To refer to a single element of a hash, you will use the hash variable name followed by the "key" associated with the value in curly brackets.Here is a simple example of using hash variables −Example#!/usr/bin/perl %data = ('John Paul', 45, 'Lisa', 30, 'Kumar', 40); print "\$data{'John Paul'} = $data{'John Paul'}"; print "\$data{'Lisa'} = $data{'Lisa'}"; print "\$data{'Kumar'} = $data{'Kumar'}";OutputThis will produce the following result −$data{'John Paul'} = 45 $data{'Lisa'} = 30 $data{'Kumar'} = 40
Read MorePerl Variable Context
Perl treats the same variable differently based on Context, i.e., the situation where a variable is being used. Let's check the following example −Example#!/usr/bin/perl @names = ('John Paul', 'Lisa', 'Kumar'); @copy = @names; $size = @names; print "Given names are : @copy"; print "Number of names are : $size";OutputThis will produce the following result −Given names are : John Paul Lisa Kumar Number of names are : 3Here @names is an array, which has been used in two different contexts. First, we copied it into another array, i.e., list, so it returned all the elements assuming that context is ...
Read MorePerl Numeric Scalars
A scalar is most often either a number or a string. Following example demonstrates the usage of various types of numeric scalars −Example#!/usr/bin/perl $integer = 200; $negative = -300; $floating = 200.340; $bigfloat = -1.2E-23; # 377 octal, same as 255 decimal $octal = 0377; # FF hex, also 255 decimal $hexa = 0xff; print "integer = $integer"; print "negative = $negative"; print "floating = $floating"; print "bigfloat = $bigfloat"; print "octal = $octal"; print "hexa = $hexa";OutputThis will produce the following result −integer = 200 negative = -300 floating = 200.34 bigfloat = -1.2e-23 octal = 255 hexa = 255
Read MorePerl String Scalars
The following example demonstrates the usage of various types of string scalars. Notice the difference between single-quoted strings and double-quoted strings −Example#!/usr/bin/perl $var = "This is string scalar!"; $quote = 'I m inside single quote - $var'; $double = "This is inside single quote - $var"; $escape = "This example of escape -\tHello, World!"; print "var = $var"; print "quote = $quote"; print "double = $double"; print "escape = $escape";OutputThis will produce the following result −var = This is string scalar! quote = I m inside single quote - $var double = This is inside single quote - This ...
Read MoreMultiline Strings in Perl
If you want to introduce multiline strings into your programs, you can use the standard single quotes as below −Example#!/usr/bin/perl $string = 'This is a multiline string'; print "$string";OutputThis will produce the following result −This is a multiline stringYou can use "here" document syntax as well to store or print multiline as below −Example#!/usr/bin/perl print
Read MoreV-Strings in Perl
A literal of the form v1.20.300.4000 is parsed as a string composed of characters with the specified ordinals. This form is known as v-strings.A v-string provides an alternative and more readable way to construct strings, rather than use the somewhat less readable interpolation form "\x{1}\x{14}\x{12c}\x{fa0}".They are any literal that begins with a v and is followed by one or more dot-separated elements. For example −Example#!/usr/bin/perl $smile = v9786; $foo = v102.111.111; $martin = v77.97.114.116.105.110; print "smile = $smile"; print "foo = $foo"; print "martin = $martin";OutputThis will also produce the same result −smile = ☺ foo = foo martin = ...
Read MorePerl Special Literals
Let me tell you about three special literals __FILE__, __LINE__, and __PACKAGE__ represent the current filename, line number, and package name at that point in your program.They may be used only as separate tokens and will not be interpolated into strings. Check the below example −Example#!/usr/bin/perl print "File name ". __FILE__ . ""; print "Line Number " . __LINE__ .""; print "Package " . __PACKAGE__ .""; # they can not be interpolated print "__FILE__ __LINE__ __PACKAGE__";OutputThis will produce the following result −File name hello.pl Line Number 4 Package main __FILE__ __LINE__ __PACKAGE__
Read MoreAccessing Array Elements in Perl
When accessing individual elements from an array in Perl, you must prefix the variable with a dollar sign ($) and then append the element index within the square brackets after the name of the variable. For example −Example#!/usr/bin/perl @days = qw/Mon Tue Wed Thu Fri Sat Sun/; print "$days[0]"; print "$days[1]"; print "$days[2]"; print "$days[6]"; print "$days[-1]"; print "$days[-7]";OutputThis will produce the following result −Mon Tue Wed Sun Sun MonArray indices start from zero, so to access the first element you need to give 0 as indices. You can also give a negative index, in which case you select the ...
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