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Perl - a quick reminder and revision. Test yourself!

At the start of the second day of my second Perl course this week (yes, really!!) I put up a quick revision of what I had covered on the first day for my not - really - new - to - Perl group. How many of these things are you familiar with?

Comments ...

Don't forget to comment your code!
- # to end of line
- after __END__ on the end of the file
- "Documentation comments" via POD ... =head (etc) to =cut

Variables ...

$ - scalar. Integer, Float, String ... Reference, Regex
@ - list. Indexed ordered collection of scalars []
% - hash. Keyed unordered collection of scalars {}
& - code. a.k.a. a "sub"
  - file handle [no special start character)
* - typeglob - one of each of the above

Strings ...

" and ' (operator and literal). operator expanding $ @ \
Also qq and q, and "here documents"

Testing ...

== numeric equality !=
eq string equality ne
=~ string match !~

Regular Expressions contain ...

- literals. A 3 @ \+ \.
- char groups [A-Z] [^aeiou] . \s \d \w \W \D \S
- counts * ? + {2,6}
- anchors ^ $ \b
- captures ()
- alternation |
/.../ m!...! m/.../

Special Variables...

$& - the bit that matched
@_ - parameters to a sub
$1 - first interesting bit ...
@ARGV - incoming parameters to program
%ENV - environment variables
@INC - where modules may load from
%INC - where modules have been loaded from
$_ - default input and pattern matching space

Conditionals ...

if, unless, and, or, &&, ||, ? ... :

Loops ...

while, for, foreach, goto (yuk!), do while, until
last, next, redo

On a public Perl course, I would expect to take much longer than just one day to cover this little lot!


(written 2011-08-26)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
P050 - Perl - General
  [4301] Perl - still a very effective language indeed for extracting and reporting - (2014-09-20)
  [4296] Polishing the Perl courses - updated training - (2014-09-17)
  [3911] How well do you know Perl and / or Python? - (2012-11-04)
  [3902] Shell - Grep - Sed - Awk - Perl - Python - which to use when? - (2012-10-22)
  [3823] Know Python or PHP? Want to learn Perl too? - (2012-07-31)
  [3332] DNA to Amino Acid - a sample Perl script - (2011-06-24)
  [3322] How much has Perl (and other languages) changed? - (2011-06-10)
  [3093] How many toilet rolls - hotel inventory and useage - (2010-12-18)
  [2971] Should the public sector compete with businesses? and other deep questions - (2010-09-26)
  [2825] Perl course - is it tailored to Linux, or Microsoft Windows? - (2010-06-25)
  [2783] The Perl Survey - (2010-05-27)
  [2736] Perl Course FAQ - (2010-04-23)
  [2504] Learning to program in ... - (2009-11-15)
  [2374] Lead characters on Perl variable names - (2009-08-24)
  [2242] So what is this thing called Perl that I keep harping on about? - (2009-06-15)
  [2228] Where do I start when writing a program? - (2009-06-11)
  [1897] Keeping on an even keel - (2008-11-21)
  [1750] Glorious (?) 12th August - what a Pe(a)rl! - (2008-08-12)
  [743] How to debug a Perl program - (2006-06-04)
  [400] New in the shops - (2005-08-01)
  [116] The next generation of programmer - (2004-11-13)

P251 - Perl Review
  [3430] Sigils - the characters on the start of variable names in Perl, Ruby and Fortran - (2011-09-10)
  [3042] Least Common Ancestor - what is it, and a Least Common Ancestor algorithm implemented in Perl - (2010-11-11)
  [3007] Setting up a matrix of data (2D array) for processing in your program - (2010-10-21)


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