Hello & Welcome to our community. Is this your first visit? Register
Follow us on
Follow us on Facebook Follow us on Twitter Watch us on YouTube


MMOCoin

Likes Likes:  0
Results 1 to 1 of 1
  1. #1
    Premium
    G4M3R's Avatar
    Join Date
    Mar 2013
    Location
    LEGEN....wait for it....DARY!
    Posts
    33
    Post Thanks / Like
    Rep Power
    12
    Reputation
    38

    Arrow >>Perl Basics 1<<


    Register to remove this ad
    Perl is a Programming Language

    Written by Larry Wall in late 80's to process mail on Unix systems and since extended by a huge cast of characters. The name is said to stand for:

    Pathologically Eclectic Rubbish Lister

    Practical Extraction and Report Language
    Perl Properties

    Interpreted Language

    "Object-Oriented"

    Cross-platform

    Forgiving

    Great for text

    Extensible, rich set of libraries

    Popular for web pages

    Extremely popular for bioinformatics

    Some Simple Scripts

    Here are some simple scripts to illustrate the "look" of a Perl program.
    Print a Message to the Terminal

    Code:
    # file: message.pl print "When that Aprill with his shoures soote\n"; print "The droghte of March ath perced to the roote,\n"; print "And bathed every veyne in swich licour\n"; print "Of which vertu engendered is the flour...\n";
    Output:

    (~) 50% perl message.plWhen that Aprill with his shoures sooteThe droghte of March ath perced to the roote,And bathed every veyne in swich licourOf which vertu engendered is the flour...
    Do Some Math

    Code:
    # file: math.pl print "2 + 2 =", 2+2, "\n"; print "log(1e23)= ", log(1e23), "\n"; print "2 * sin(3.1414)= ", 2 * sin(3.1414), "\n";
    Output:

    (~) 51% perl math.pl2 + 2 =4log(1e23)= 52.95945713886312 * sin(3.1414)= 0.000385307177203065
    Run a System Command

    Code:
    # file: system.pl system "ls";
    Output:

    (~/docs/grad_course/perl) 52% perl system.plindex.html math.pl~ problem_set.html~ what_is_perl.htmlindex.html~ message.pl simple.html what_is_perl.html~math.pl problem_set.html simple.html~
    Return the Time of Day

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

    (~) 53% perl time.plThe time is now Thu Sep 16 17:30:02 1999Mechanics of Writing Perl Scripts

    Some hints to help you get going.
    Creating the Script



    A Perl script is just a text file. Use any text (programmer's) editor.
    By convention, Perl script files end with the extension .pl.
    The Emacs text editor has a Perl mode that will auto-format your Perl scripts and highlight keywords. Perl mode will be activated automatically if you end the script name with .pl. Otherwise, you can force Emacs to enter Perl mode by placing this line somewhere near the top of the file:

    # -*- mode: perl -*-
    The next time you open the file, Emacs will enter Perl mode.
    Running the Script

    Option 1Run the perl program from the command line, giving it the name of the script file to run.

    (~) 50% perl time.pl The time is now Thu Sep 16 18:09:28 1999
    Option 2Put the magic comment #!/usr/bin/perl at the top of the script.
    #!/usr/bin/perl# file: time.pl$time = localtime;print "The time is now $time\n";
    Make the script executable with chmod +x time.pl:

    (~) 51% chmod +x time.pl
    Run the script as if it were a command:

    (~) 52% time.pl The time is now Thu Sep 16 18:12:13 1999
    Common Errors

    Every script goes through a few iterations before you get it right. Here are some common errors:
    Syntax Errors

    Code:
    #!/usr/bin/perl # file: time.pl time = localtime; print "The time is now $time\n";
    Output:

    (~) 53% time.plCan't modify time in scalar assignment at time.pl line 3, near "localtime;"Execution of time.pl aborted due to compilation errors.
    Runtime Errors

    Code:
    #!/usr/bin/perl # file: math.pl $six_of_one = 6; $half_dozen = 12/2; $result = $six_of_one/($half_dozen - $six_of_one); print "The result is $result\n";
    Output:

    (~) 54% math.plIllegal division by zero at math.pl line 6.
    Forgetting to Make the Script Executable


    (~) 55% test.pltest.pl: Permission denied.
    Getting the Path to Perl Wrong on the #! line

    Code:
    #!/usr/local/bin/pearl # file: time.pl $time = localtime; print "The time is now $time\n";

    (~) 55% time.pltime.pl: Command not found.
    Useful Perl Command-Line Options

    You can call Perl with a few command-line options to help catch errors:
    -cPerform a syntax check, but don't run.-wTurn on verbose warnings.-dTurn on the Perl debugger.Usually you will invoke these from the command-line, as in perl -cw time.pl (syntax check time.pl with verbose warnings). You can also put them in the top line: #!/usr/bin/perl -w.


    CHECK OUT Perl Basics 2!




    › See More: >>Perl Basics 1<<
    Last edited by G4M3R; 23-03-13 at 06:36 PM.



  2. Related Threads - Scroll Down after related threads if you are only interested to view replies for above post/thread

 

 

Visitors found this page by searching for:

Nobody landed on this page from a search engine, yet!
SEO Blog

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
All times are GMT -5. The time now is 03:41 AM.
Powered by vBulletin® Copyright ©2000-2024, Jelsoft Enterprises Ltd.
See More links by ForumSetup.net. Feedback Buttons provided by Advanced Post Thanks / Like (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.
vBulletin Licensed to: MMOPro.org