1.  History  Ease of use  Portability  Standard  Security & Privacy  User support  Application &Popularity Today  Ten Most Popular Programming Languages COOL

2.  Practical Extraction & Report Language(PERL)  Developed by Larry Wall in 1987  Combined features of C, awk, Sed, Bourne  Efficient use for manipulation of text files.  Efficient use for report processing  Motto: “there is more than one way to do it”  Contains multiple versions

4.  Very easy to use and understand  Designed with syntax similar to human language  Has features that make it easy to program ex:  Automatic memory management  List  Dynamic Typing  Regular Expression allow manipulation of text

5.  Among the most portable programming languages  Can be compiled over 70 Operating Systems  Can pick up a Perl program and compile it on another computer  Almost no need to modify the program

6.  Keywords  Instructions Perl recognizes and understand. Ex: Print, Die, Return Should not be re  Statements Print: “hello world/n”  Blocks Enclosed in braces { print “This is”; print “a block”; print “of statements”; }

7.  Perl has 3 basic types of variables 1. Scalar Holds a single type of value, preceded by a dollar sign Can be a string, a number, or a reference $foo = 1; Types of value that can be assigned to a number : 12345 # integer -54321 # negative integer 12345.67 # floating point 6.02E23 # scientific notation 0xffff # hexadecimal

8.  Perl has 3 basic types of variables 2- Arrays holds multiple values, preceded by the @ sign @color ={ “red”, “blue”, “green”}; Its index start at 0, print the first element of array print “$color[0]\n”; // to print red

9.  Perl has 3 basic types of variables 3- Hash Unordered collection of values Each value can be retrieved by its key Hash name is preceded by a % sign Declared by : Hash Name -> Key -> Value % pages = ( "fred", "http://www.cgi101.com/~fred/", "beth", "http://www.cgi101.com/~beth/", "john", “http://www.cgi101.com/~john/" );

10.  Perl also contains:  If … else statements  If( expression) {execute this} else {execute this};  More than four different types of loop  While loop  For loop  Foreach loop  Until loop

11.  Perl also contains  Control commands Last: terminates the execution of a loop Next: makes the loop go to its next iteration Redo: makes loop restart without evaluating loop conditions  Modifiers Allow any statement to loop based on some conditions  Statements if expression  Statements until/unless expression  Statements while expression

12.  Perl also contains  Regular Expressions They are String literals Used to find and replace strings by using patterns s/pattern/replace/ ->searches $_ by default, replace  Subroutines Defined using keyword sub sub (name) {block}; $subref=sub{block}; #creates anonymous subroutine

13.  Privacy  Privacy is not enforced in Perl “Perl does not enforce private and public part of its module as …in…C++, Ada, Modula-17” Module is a fundamental unit of code reuse in Perl  Security  Perl has features that make it secure  Can handle insecure data by using Taint mode  Taint mode can be set automatically  Things that come outside your program is tainted  Tainted data are restricted in what they can do

14.  Has a vast community of support that has  User Groups o Have mongers in many cities around the world  Workshops o Teach Perl during workshops at different level  Hackathons o Perl hackers gather to hack on specific projects for days  Two Major Annual Conventions o Perl Conference o Yet Another Perl Conference (YAPC)

15.  Application  Used to write CGI scripts  Popular for writing web applications  Many large projects are written in Perl Cpanel, a UNIX web based hosting panel Bugzilla, web tracker developed by Mozilla Twiki, Perl based structured wiki application Amazon, Priceline, Craigslist  Popularity  Perl is the 8 th top programming language in 2010