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Perl Programming
TopicsIntroduction to PerlVariables
ScalarsArraysHashes
Regular Expressions
IntroductionPerl – Practical Extraction and Reporting
LanguageDeveloped in 1987 by Larry WallFilenames should have the extension of .plRuns under windows and linuxThe first line of perl under linux is
#!/usr/bin/perlThe first line of perl under windows is
#!c:/perl/bin/perl.exe
IntroductionPerl scripts are interpreted in the command
or shell prompt and even in the browser. If it in the browser, a Http header should be
set likeprint “Content-type: text/html \n\n”;
First example#! C:/perl/bin/perl.exeprint “Content-type: text/html \n\n”;Print “Hello World “;
IntroductionGo to the command prompt and execute the
command perl filename.pl
In the browser, type http://localhost/filename.pl
Perl VariablesScalars ($)
Numbers or Strings or referenceStarted with a $ symbol Ex. $string=“Hello “; $a=200; $x=2**3;
Arrays (@)List of scalar dataDefined by an @ symbol@s=(“hello”, ”world”);
Hashes (%)Complex list with both a key and a value part for each
element of the list.Defined by a % symbol%ages = ("Jerry", 45, "Tom", 22, "Vickie", 38);
Scalars$x = 12345; # integer $x = 12345.67; # floating point $x = 6.02e23; # scientific notation $x = 4_294_967_296; # underline for legibility $x = 0377; # octal $x = 0xffff; # hexadecimal $x = 0b1100_0000; # binary$x=“Hello” # string literalsDouble quotes – variables are interpolatedSingle quotes – variables are not interpolated
Arrays@a=(“hi”,”Hello”,”there”);Print @a;$c=pop @a; # last element “there” is stored
in cPush(@a,”here”);Print @a;Print $a[0]; #index starts at 0, so prints hi
HashesUses a key value pairKey is usually a string literalExample
%hash=(“Tom”,33,”mike”,23,”john”,19);Print %hash;@k=keys %hash;@v=values %hash;$count=keys %hash;While(($keys=>$values)=each %hash){print “$keys=>$values”.”<br/>”;}
Regular ExpressionMatches a word or a phrase or even a
character trying to match a patternMeta charactersPattern Modifiers