3. Introduction Perl – Practical Extraction and Reporting Language Developed in 1987 by Larry Wall Filenames should have the extension of .pl Runs under windows and linux The first line of perl under linux is #!/usr/bin/perl The first line of perl under windows is #!c:/perl/bin/perl.exe
4. Introduction Perl 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 like print “Content-type: text/html ”; First example #! C:/perl/bin/perl.exe print “Content-type: text/html ”; Print “Hello World “;
5. Introduction Go to the command prompt and execute the command perl filename.pl In the browser, type http://localhost/filename.pl
6. Perl Variables Scalars ($) Numbers or Strings or reference Started with a $ symbol Ex. $string=“Hello “; $a=200; $x=2**3; Arrays (@) List of scalar data Defined 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);
7. 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 literals Double quotes – variables are interpolated Single quotes – variables are not interpolated
8. Arrays @a=(“hi”,”Hello”,”there”); Print @a; $c=pop @a; # last element “there” is stored in c Push(@a,”here”); Print @a; Print $a[0]; #index starts at 0, so prints hi
9. Hashes Uses a key value pair Key is usually a string literal Example %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/>”;}
10. Regular Expression Matches a word or a phrase or even a character trying to match a pattern Meta characters Pattern Modifiers
