Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
lists / context demo
Subroutines in Perl example from a Well House Consultants training course
More on Subroutines in Perl [link]

This example is described in the following article(s):
   • Seven new intermediate Perl examples - [link]

Source code: l2 Module: P209

=head1 Lists and Context

* If you use an @abc, you mean the WHOLE of a list
* If you use $abc[10], you mean a scalar member of a list
* If you use $#abc, you mean the top index number of a list

* If you refer to a list IN A LIST CONTEXT you mean all elements
* In a SCALAR context, you mean the NUMBER OF ELEMNST in the list
* In a DOUBLE QUOTE context, you mean a string of all element ...
  ... linked with a space between each of them

# A list - starts with an @
@wentto = ("Lacock","Calne","Cherhill","Avebury");

# HOWEVER - members are scalars, so start with a $
print "First place was $wentto[0]\n";

# Refer to a list but in a scalar context
# means the LENGTH of the list!
$nplace = @wentto;
print "We went to $nplace places\n";

# List starts at zero, so last element is
# numbered one LESS THAT the number of elements
print "Our last stop was $wentto[$nplace-1]\n";

# As an alternative, $# returns LAST POSITION
print "Our last stop was $wentto[$#wentto]\n";

# Or ... you can count down from the top
print "Our last stop was $wentto[-1]\n";

# List or scalar context - with or without spaces
print "All the places ",@wentto,"\n";
print "All the places @wentto\n";
# In a scalar context - NUMBER of elements
print "Count the places: ",@wentto+0,"\n";

$places = join(", ",@wentto);
$places =~ s/(.*),/\1 and/;
print $places,"\n";


Dorothy:p82 grahamellis$ perl l2
First place was Lacock
We went to 4 places
Our last stop was Avebury
Our last stop was Avebury
Our last stop was Avebury
All the places LacockCalneCherhillAvebury
All the places Lacock Calne Cherhill Avebury
Count the places: 4
Lacock, Calne, Cherhill and Avebury
Dorothy:p82 grahamellis$

Learn about this subject
This module and example are covered on the following public courses:
 * Perl Programming
 * Perl bootcamp
 * Learning to program in Perl
 * Perl Programming
Also available on on site courses for larger groups

Books covering this topic
Yes. We have over 700 books in our library. Books covering Perl are listed here and when you've selected a relevant book we'll link you on to Amazon to order.

Other Examples
This example comes from our "Subroutines in Perl" training module. You'll find a description of the topic and some other closely related examples on the "Subroutines in Perl" module index page.

Full description of the source code
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources
• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
The Horse's mouth provides a daily tip or thought.
• Further resources are available via the resources centre.
• All of these resources can be searched through through our search engine
• And there's a global index here.

Purpose of this website
This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

Web site author
This web site is written and maintained by Well House Consultants.

Conditions of use
Past attendees on our training courses are welcome to use individual examples in the course of their programming, but must check the examples they use to ensure that they are suitable for their job. Remember that some of our examples show you how not to do things - check in your notes. Well House Consultants take no responsibility for the suitability of these example programs to customer's needs.

This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details.

Any of our images within this code may NOT be reused on a public URL without our prior permission. For Bona Fide personal use, we will often grant you permission provided that you provide a link back. Commercial use on a website will incur a license fee for each image used - details on request.

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2022: 48 Spa Road • Melksham, Wiltshire • United Kingdom • SN12 7NY
PH: 01144 1225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/resources/ex.php • PAGE BUILT: Sun Oct 11 14:50:09 2020 • BUILD SYSTEM: JelliaJamb