www.RogerWendell.com
Roger J. Wendell
Defending 3.8 Billion Years of Organic EvolutionSM
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Perl Logo Perl:
  • Practical Extraction and Reporting Language
  • Perl is a general-purpose programming language that was developed by Larry Wall. First released in 1987, Perl was originally developed for text manipulation but is now used for wide range of tasks. Perl has become a popular language for writing CGI scripts and is easy to use for building and testing simple programs...

 

 

"Perl is the Swiss Army chainsaw of scripting languages: powerful and adaptable."
(From O'Reilly's Beginner's Introduction to Perl)

 

Arrow Pointing Right Click Here for my main computer page...
Arrow Pointing Right Click Here for my UNIX page...

 

"I programmed for the most part in the first year or so in Perl; and Craigslist, these days, it's pretty much all Perl."
- Craig Newmark, founder of Craigslist
(in a July 2008 interview by Timothy M. O'Brien at the Personal Democracy Forum in New York)

 

Wirth's Law:    "Software is getting slower more rapidly than hardware becomes faster."

 

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Y = CX^2 + B
Perl Parabola 12-25-2007
pico parabola.pl
perl parabola.pl -2 3
cat parabola.data
gnuplot
plot "parabola.data"
quit
#!/usr/bin/perl
# experimenting with a parabola 12-25-2007
# c is the concavity of the parabola
# Y = CX^2 + B
# B is the intercept with the Y axis
# ARGV is argument variable containing the arguments
# to the program on the command line
 
$c = $ARGV[0]; $b = $ARGV[1]; open (filehandle, ">parabola.data");
for ( $x = -10; $x<=10; $x=$x+.1 )
 
{
       $y = $c * $x * $x + $b;
       print filehandle $x, " ", $y, "\n";
 
}  
close (filehandle);

 

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Perl Camel Basics

Under UNIX, Perl acts like a shell interpreter.
Most UNIX systems store Perl in /usr/bin/perl

 

In Perl, numbers and strings are the basic unit of conversation and are called scalars. Scalars that represent information that does not change over the life of the program are called constants or literals. Examples of literals are pi (3.14159265...), the name of the fourth planet from the sun (Mars), or the absolute limit of causal interation (299,792,458 metres per second [1,079,252,849 km/h]).

In Perl, scalars that change are called scalar variables. You can change the contents of a variable because they merely act as as handles for the data they represent. Variable are usually given convenient and easy-to-remember names that allow you to easily refer to the data you are manipulating.

 

Perl Camel - Small Perl Operators

 

Perl Camel - Small Simple bits of Code:

Hello, world!
  #!/usr/local/bin/perl 
   print "Hello, world!\n"; 

 

 

Current Time
# file: time.pl
  $time = localtime;
  print "The time is now $time\n";

 

 

A Simple Calculator

while(<STDIN>) {
    $i = $_; chomp($i); unless($i) { last }
    $o = eval($i); print "Answer = $o\n";
}

 

 

 

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Perl Camel - Small Perl References and Related Stuff:

 

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A Really Bad Computer Day This site best viewed with a Computer and a Monitor!

 

More Links:

  1. 1728 All kinds of online calculators!
  2. Arachnophilia - the Paul Lutus CareWare page
  3. Bug Me Not - Avoid Internet registrations
  4. Central Ops - Free online network utilities
  5. CGI Scripts
  6. CNet
  7. Colors in HTML - 16 million of 'em!
  8. Computer Suff - by me!
  9. CrackSpider
  10. Crucial Memory. It's Curcial.
  11. Debian - free operating system
  12. DMOZ - Open Directory Project
  13. Drupal
  14. Entity References
  15. Eprompter Free Email Retrieval and Notification
  16. Ghostscript, Gohstview, and GSview
  17. GNOME Project - Free desktop environment
  18. GNU Project - Free Unix-like operating system
  19. HTML Character Reference by Webreference.com
  20. HTML Character Set by Walter Ian Kaye
  21. HTML Ordered Lists
  1. JavaScript Source - "...an excellent JavaScript resource"
  2. Launchpad - services for projects in the open source universe
  3. Memory Hole Resucing knowledge, freeing information
  4. Mozilla Foxfire webrowswer (free!)
  5. Nyx - Spirit of the Night (free Unix shell accounts)
  6. Open Office
  7. Open Source Initiative
  8. PGP by me!
  9. Protonic "free fast technical support"
  10. Raspberry PI
  11. Slash Dot News for Nerds. Stuff that matters.
  12. SDF - Super Dimension Fortress (a networked community of free software authors...)
  13. Softpedia The encyclopedia of free software downloads!
  14. Source Forge - Find and Develop Open Source Software
  15. Test Page that allows me to test stuff!
  16. Unicode Consortium
  17. Ubuntu - UNIX for Humans!
  18. Unix
  19. Validome HTML / XHTML / WML / XML Validator
  20. W3 World Wide Web Consortium
  21. Wayback Machine - Internet Archive

 

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