http://www.perlmonks.org?node_id=226525
Order Perl by Example

Item Description: Written by Ellie Quigley, Published by Prentice Hall

Review Synopsis: Update to the first review

A well thought out book that is very useful to have. I would rank it up there with Perl In a Nutshell.
Takes you through almost everything and it uses code
that is easy to follow and implement. Very understandable.

Each sample is written in a clear format. First the script, then the output and then an explaination of the script. There
are 13 chapters that cover Variables, Operators, Regex, Conditionals,
FileHandles, Subs, Interfacing, and much more. Each code sample is quite easy to follow You'll learn exactly what you need to know--and every new function is demonstrated.

The book evolved from a Perl Programming class at the University of California.
Hard to find, but worth the search.

Here is a sample;


$firstVar  = 20;
$secondVar = 20;

$firstVar++ if ($secondVar == 10);

print("firstVar  = $firstVar\n");
print("secondVar = $secondVar\n");

This program prints:

firstVar  = 20
secondVar = 20


The program doesn't increment $firstVar because the value of $secondVar is 20 at 
the time the condition is evaluated. If you changed the 10 to a 20
in the condition, Perl would increment $firstVar.