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diff --git a/perl.html.markdown b/perl.html.markdown new file mode 100644 index 00000000..7e0b1183 --- /dev/null +++ b/perl.html.markdown @@ -0,0 +1,122 @@ +--- +name: perl +category: language +language: perl +filename: learnperl.pl +contributors: + - ["Korjavin Ivan", "http://github.com/korjavin"] +--- + +Perl 5 is a highly capable, feature-rich programming language with over 25 years of development. + +Perl 5 runs on over 100 platforms from portables to mainframes and is suitable for both rapid prototyping and large scale development projects. + +```perl +# Single line comments start with a hash. + +/* +Multi-line comments look like this. +*/ + + +#### Perl variable types + +# Variables begin with the $ symbol. +# A valid variable name starts with a letter or underscore, +# followed by any number of letters, numbers, or underscores. + +### Perl has three main variable types: scalars, arrays, and hashes. + +## Scalars +# A scalar represents a single value: +my $animal = "camel"; +my $answer = 42; + +# Scalar values can be strings, integers or floating point numbers, and Perl will automatically convert between them as required. + +## Arrays +# An array represents a list of values: +my @animals = ("camel", "llama", "owl"); +my @numbers = (23, 42, 69); +my @mixed = ("camel", 42, 1.23); + + + +## Hashes +# A hash represents a set of key/value pairs: + +my %fruit_color = ("apple", "red", "banana", "yellow"); + +# You can use whitespace and the "=>" operator to lay them out more nicely: + +my %fruit_color = ( + apple => "red", + banana => "yellow", + ); +# Scalars, arrays and hashes are documented more fully in perldata. (perldoc perldata). + +# More complex data types can be constructed using references, which allow you to build lists and hashes within lists and hashes. + +#### Conditional and looping constructs + +# Perl has most of the usual conditional and looping constructs. + +if ( $var ) { + ... +} elsif ( $var eq 'bar' ) { + ... +} else { + ... +} + +unless ( condition ) { + ... + } +# This is provided as a more readable version of "if (!condition)" + +# the Perlish post-condition way +print "Yow!" if $zippy; +print "We have no bananas" unless $bananas; + +# while + while ( condition ) { + ... + } + + +# for and foreach +for ($i = 0; $i <= $max; $i++) { + ... + } + +foreach (@array) { + print "This element is $_\n"; + } + + +#### Regular expressions + +# Perl's regular expression support is both broad and deep, and is the subject of lengthy documentation in perlrequick, perlretut, and elsewhere. However, in short: + +# Simple matching +if (/foo/) { ... } # true if $_ contains "foo" +if ($a =~ /foo/) { ... } # true if $a contains "foo" + +# Simple substitution + +$a =~ s/foo/bar/; # replaces foo with bar in $a +$a =~ s/foo/bar/g; # replaces ALL INSTANCES of foo with bar in $a + + +``` + +#### Using Perl modules + +# Perl modules provide a range of features to help you avoid reinventing the wheel, and can be downloaded from CPAN ( http://www.cpan.org/ ). A number of popular modules are included with the Perl distribution itself. + +# perlfaq contains questions and answers related to many common tasks, and often provides suggestions for good CPAN modules to use. + +#### Further Reading + +[Learn at www.perl.com](http://www.perl.org/learn.html) + and perldoc perlintro |