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!

 

Links:

  1. 0Spam (Zero Spam)
  2. Annoyances Fixing problems with Microsoft Windows
  3. Anti-Phishing
  4. Arachnophilia - the Paul Lutus CareWare page
  5. Avast - free Anti-Virus
  6. AVG Anti-Virus
  7. Bitmek "Let the power of the Internet work for you!"
  8. Button generator
  9. Button maker by Cool Archive
  10. Central Ops - Free online network utilities
  11. CGI Scripts
  12. Colors in HTML - 16 million of 'em!
  13. Computer History Museum
  14. Computer Stuff - by me!
  15. CrackSpider
  16. Debian - free operating system
  17. Dillo - speedy, small footprint web browser (free!)
  18. DMOZ - Open Directory Project
  19. Drupal
  20. Entity References
  21. Eprompter Free Email Retrieval and Notification
  22. Flaming Text
  23. Foxit - Free pdf viewer
  24. Ghostscript, Gohstview, and GSview
  25. GNOME Project - Free desktop environment
  26. GNU Project - Free Unix-like operating system
  27. HTML Character Reference
  28. HTML Character Set by Walter Ian Kaye
  29. HTML Ordered Lists
  30. Infinite Monkeys Eclectic Software
  31. JavaScript Source - "...an excellent JavaScript resource"
  32. K7 Net Unified Messaging
  33. Keir.net - Robin Keir's software utilites page
  34. Kephyr - Nice software for nice people
  35. Launchpad - services for projects in the open source universe
  36. Libre Office - free office software by the Document Foundation
  37. Lynx text browser
  38. Memory Hole Resucing knowledge, freeing information
  1. Mozilla Foxfire webrowswer (free!)
  2. My Memorizer - A free reminder service!
  3. Nyx - Spirit of the Night (free Unix shell accounts)
  4. Old Version - Because newer is not always better
  5. Open Office
  6. Open Source Initiative
  7. PC Hell
  8. PC Pitstop free automated tests...
  9. Perl - by me!
  10. Perl - The source for Perl
  11. Perl Directory
  12. Pic Search
  13. PGP by me!
  14. Protonic "free fast technical support"
  15. PuTTY - a client program for the SSH, Telnet and Rlogin network protocols
  16. Python programming language
  17. Raspberry Pi - tiny and affordable computers...
  18. RoundCube - open source webmail software
  19. SDF - Super Dimension Fortress (a networked community of free software authors...)
  20. Save This
  21. SD Card Formatter
  22. Softpedia The encyclopedia of free software downloads!
  23. Source Forge - Find and Develop Open Source Software
  24. Special Alt Characters
  25. Spell Checker (Online)
  26. SpyBot Search and Destroy!
  27. TechDirt - government policy, technology and legal issues
  28. Test Page that allows me to test stuff!
  29. Toast Net Connection Performance Test
  30. Unicode Consortium
  31. Ubuntu - UNIX for Humans!
  32. Unix, Linux, and Raspberry Pi - by me!
  33. Validome HTML / XHTML / WML / XML Validator
  34. VideoLAN - a great media player!
  35. W3 World Wide Web Consortium
  36. Wayback Machine - Internet Archive
  37. What's My DNS? - DNS Server Testing Tool
  38. ZamZar - Free online File Conversion

 

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