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Introduction to Perl Part I By: Cdric Notredame (Adapted from BT McInnes)

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2 What is Perl? Perl is a Portable Scripting Language No compiling is needed. Runs on Windows, UNIX, LINUX and cygwin Fast and easy text processing capability Fast and easy file handling capability Written by Larry Wall Perl is the language for getting your job done. Too Slow For Number Crunching Ideal for Prototyping

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3 How to Access Perl To install at home Perl Comes by Default on Linux, Cygwin, MacOSX www.perl.com Has rpm's for Linux www.perl.com www.activestate.com Has binaries for Windows www.activestate.com Latest Version is 5.8 To check if Perl is working and the version number % perl -v

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4 Resources For Perl Books: Learning Perl By Larry Wall Published by O'Reilly Programming Perl By Larry Wall,Tom Christiansen and Jon Orwant Published by O'Reilly Web Site http://safari.oreilly.com Contains both Learning Perl and Programming Perl in ebook form

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5 Web Sources for Perl Web www.perl.com www.perldoc.com www.perl.org www.perlmonks.org

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6 The Basic Hello World Program which perl pico hello.pl Program: #! /path/perl -w print Hello World!\n; Save this as hello.pl Give it executable permissions chmod a+x hello.pl Run it as follows:./hello.pl

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7 Hello World Observations .pl extension is optional but is commonly used The first line #!/usr/local/bin/perl tells UNIX where to find Perl -w switches on warning : not required but a really good idea

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Variables and Their Content

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9 Numerical Literals 6Integer 12.6Floating Point 1e10Scientific Notation 6.4E-33Scientific Notation 4_348_348Underscores instead of commas for long numbers

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10 String Literals There is more than one way to do it! 'Just don't create a file called -rf.' Beauty?\nWhat's that?\n Real programmers can write assembly in any language. Quotes from Larry Wall

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11 Types of Variables Types of variables: Scalar variables : $a, $b, $c Array variables : @array Hash variables : %hash File handles : STDIN, STDOUT, STDERR Variables do not need to be declared Variable type (int, char,...) is decided at run time $a = 5; # now an integer $a = perl; # now a string

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12 Operators on Scalar Variables Numeric and Logic Operators Typical : +, -, *, /, %, ++, --, +=, -=, *=, /=, ||, &&, ! ect Not typical: ** for exponentiation String Operators Concatenation: . - similar to strcat $first_name = Larry; $last_name = Wall; $full_name = $first_name. . $last_name;

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13 Equality Operators for Strings Equality/ Inequality : eq and ne $language = Perl; if ($language == Perl)...# Wrong! if ($language eq Perl)...#Correct Use eq / ne rather than == / != for strings

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14 Relational Operators for Strings Greater than Numeric : >String : gt Greater than or equal to Numeric : >=String : ge Less than Numeric :