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7. 5.32.0 Documentation - Perl Language

This is the first part of the Perl tutorial.

In this part you will learn how to install Perl on Microsoft Windows and how to startusing it on Windows, Linux or on a Mac.

You'll get directions to set up your development environment, or in less grandiose words:which editor or IDE to use for writing Perl?

We will also see the standard 'Hello World' example.

Perl58delta - Perldoc.perl.org

You can also watch the related video.

Perl Production-ready, under active development Perl 5.32.0 is the current stable version of Perl. Perl is actively maintained and developed (git repository) by a large group of dedicated volunteers.Perl will be developed and maintained for many years to come. Perl extension for mac integration code GtkOSXApplication. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.12.3 or, at your option, any later version of Perl 5 you may have available. Perl -MCPAN -e shell install Gtk2::OSXApplication For more. ActiveState is pleased to announce ActivePerl 5.8.9 build 829, and ActivePerl 5.12.3 build 1204, complete, ready-to-install binary distributions of Perl. Builds for Windows, Mac OS X and Linux are made freely available. Builds for Solaris, HP-UX and AIX are available with ActivePerl Business Edition.

Windows

The latest Perl release (5.12.3 as of this writing) builds without changes under all versions of Mac OS X from 10.3 'Panther' onwards. In order to build your own version of Perl you will need 'make' this is part of the Apples developer tools (you only need the 'unix tools'), usually supplied with Mac OS install DVDs. Perl 4 went through a series of maintenance releases, culminating in Perl 4.036 in 1993, whereupon Wall abandoned Perl 4 to begin work on Perl 5.Initial design of Perl 5 continued into 1994. The perl5-porters mailing list was established in May 1994 to coordinate work on porting Perl 5 to different platforms. It remains the primary forum for development, maintenance, and porting of Perl 5.

For Windows we are going to use Strawberry Perl.

In order to get started visit the website of Strawberry Perland follow the link to download it.

Go ahead, download the exe file and install it on your system. Before doing so,please make sure you don't have any other Perl installed.

They could work together but that would require some more explanations.For now let's have one single version of Perl installed on your system.

Linux

Most Linux modern Linux distributions come with a recent version of Perl.For now we are going to use that version of Perl. For editor,you can install Padre - most Linux distribution offer it from theirofficial package management system. Otherwise you can pick any regular text editor.If you are familiar with vim or Emacs, use the one you like. OtherwiseGedit might be a good simple editor.

Apple

I believe Macs also come with Perl or you can easily install it viathe standard installation tools.

Editor and IDE

Even though it is recommended, you don't have to use the Padre IDE to write Perl code.In the next part I'll list a couple of editors and IDEs youcan use for your Perl programming. Even if you select another editorI'd recommend - for the Windows users - to install the above mentioned DWIM Perl package.

It has lots of Perl extensions bundled so it will save you a lot of time down the road.

Video

If you prefer, you can also watch theHello world with Perlvideo I uploaded to YouTube.

In that case you might also want to checkout the Beginner Perl Maven video course.

First program

Your first program will look like this:

examples/hello_world.pl

Let me explain it step-by-step.

Hello world

Once you installed DWIM Perl you can click on'Start -> All programs -> DWIM Perl -> Padre' which will open the editorwith and empty file.

Type in

As you can see statements in perl end with a semi-colon ;.The n is the sign we used to denote a newline.Strings are enclosed in double-quotes '.The print function prints to the screen.When this is executed perl will print the text and at the end it will print a newline.

Save the file as hello.pl and then you can run the code by selecting 'Run -> Run Script'You will see a separate window showing up with the output.

That's it, you wrote your first perl script.

Let's enhance it a bit.

Perl on the command line for non-Padre users

If you are not using Padre or one of the other IDEsyou won't be able to run your script from the editor itself.At least not by default. You will need to open a shell(or cmd in Windows), change to the directory where you saved the hello.plfile and type in:

Perlcc For Perl 5.12.3 For Machine Learning

perl hello.pl

That's how you can run your script on the command line.

say() instead of print()

Let's improve our one-line Perl script a bit:

First of all let's state the minimum version of Perl we would like to use:

Once you typed this in, you can run the script again by selecting'Run -> Run Script' or by pressing F5.That will automatically save the file before running it.

It is generally a good practice to tell what is the minimum version of perl your code requires.

In this case it also adds a few new features to perl including the say keyword.say is like print but it is shorter and itautomatically adds a newline at the end.

You can change your code like this:

We replaced print by say and remove the n from the end of the string.

The current installation you are using is probably version 5.12.3 or 5.14.Most modern Linux distributions come with version 5.10 or newer.

Unfortunately there are still places using older versions of perl.Those won't be able to use the say() keyword and might need some adjustmentsto the examples later. I'll point out when I am actually using featuresthat require version 5.10.

Safety net

In addition in every script I'd strongly recommend to make some further modifications tothe behavior of Perl. For this we add 2, so called pragmatas, that are very similar to compiler flagsin other languages:

examples/hello_world.pl

In this case the use keyword tells perl to load and enable each pragma.

strict and warnings will help you catch some common bugsin your code or sometimes even prevent you from making them in the first place.They are very handy.

Perl561delta - Perldoc.perl.org

User Input

Now let's improve our example by asking the user her name and includingit in the response.

examples/hello_name.pl

$name is called a scalar variable.

Variables are declared using the my keyword.(actually that's one of the requirements strict adds.)

Scalar variables always start with a $ sign.The <STDIN> is the tool to read a line from the keyboard.

Type in the above and run it by pressing F5.

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It will ask for your name. Type in your name and press ENTER to let perl knowyou have finished typing in your name.

You will notice that the output is a bit broken: The comma afterthe name appears on a newline. That's because the ENTER you pressed, when typing in your name,got into the $name variable.

Getting rid of newlines

examples/hello_name_chomp.pl

It is such a common task in Perl, that there is a special function called chompto remove the trailing newlines from strings.

Conclusion

In every script you write you should always add use strict; and use warnings;as the first two statements. It is also very recommended to add use 5.010;.

Exercises

I promised exercises.

Try the following script:

examples/hello_and_world.pl

Perl - The Perl 5 Language Interpreter - Metacpan.org

It did not show on one line. Why? How to fix it?

Exercise 2

Write a script that asks the user for two numbers, one after the other.Then prints out the sum of the two numbers.

What's next?

See Full List On Perldoc.perl.org

The next part of the tutorial is abouteditors, IDEs and development environment for Perl.

5.32.0 Documentation - Perl Language

Published on 2012-08-08