Perl Christmas Quiz 2009

Chris Jack chris_jack at
Mon Nov 30 18:24:12 GMT 2009

Seeing as last year's quiz was mildly popular, I thought I'd do another one. I've changed the mix of questions based on what people submitted answers to last year - it also arguably a little more educational this time around.

Any feedback about the quiz, either private or public is welcome. Apologies if any of it doesn't come out well formatted - it all looked fine before I hit send.



1) Without running it to check, what does the following program output?

my %a = (3,2,1,0);

for my $b (sort values %a) {
    $b += 4;

print $a{1} . "\n";


2) If you received a perl mongers award for contributions to the Perl
community, what colour/type of camel would the award be?


3) What is Perl XS? What does XS stand for?


4) Based on your answer to the previous question, what do you conclude about
Perl programmers spelling ability?


5) Write a short perl program that has a memory leak. Bonus mark for one line
solutions. Second bonus mark for the shortest program.


6) What is the name of the official Soft Toy Camel of the London Perl Mongers?
Bonus mark if you own one.


7) Write a one line program that takes a non-negative integer as an argument
and prints the square root when the answer's an integer.


Restrictions: the perl line should be a regular expression.
You are allowed to use the following functions/operators "x", "-", "length",
"print" plus any of the usual regular expression bestiary.

Hint: Consider converting the number to unary.


8) According to, what is the best selling Perl book so far in 2009?


9) What is the link for the perl v other languages videos
discussed on this list, and also the bubble sort video?


10) What is the highest value of X that is a currently available, stable
production release of perl 5.X?


11) Think of a witty and/or interesting Perl Christmas quiz question and
answer it.

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