CGI programming using Perl

CGI programming using Perl

Sam Department of Computer Science and Engineering

The Chinese University of Hong Kong

Content

Brief Introduction of Perl

Useful Techniques

CGI Example

Favorite Links to Visit

Perl

Perl is a high-level programming language Advantages:

rapid development (interpreted language)

portable across many platforms (UNIX, Windows, etc)

faster execution than shell scripts

free and huge library of free modules and scripts

Key language features and examples

1. Basic Regular Expressions (regex)

Perl's regex often look like this:

$name=~/piper/

That is saying "If 'piper' is inside $name, then True."

Key language features and examplesMore Example:

$_='My email address is <[email protected]>.';

/(<robert\@netcat.co.uk>)/i;

print "Found it ! $1\n";

Output:

Found it ! <[email protected]>

Key language features and examples2. SplittingExample:

$_='Piper:PA-28:Archer:OO-ROB:Antwerp';@details=split /:/, $_, 3;foreach (@details) { print "$_\n"; }

Output:

Piper

PA-28

Archer:OO-ROB:Antwerp


3. File OperationsExample:

$stuff="c:\scripts\stuff.txt";

open STUFF, $stuff;

while (<STUFF>) {

print "Line number $. is : $_";

}


More Example:

@ARGV="c:/scripts/out.txt";

$^I=".bk";

while (<>) {

tr/A-Z/a-z/;

print;

}


3. Associative Arrays

@myarray Vs %myhash

Index Value Key Value

0 Spain ES Spain

1 Belgium BE Belgium

2 Germany DE Germany


More Example:

%countries=('NL','The Netherlands','BE','Belgium','DE'

,'Germany','MC','Monaco','ES','Spain');

print "Enter the country code:";

chop ($find=<STDIN>);

$find=~tr/a-z/A-Z/;

print "$countries{$find} has the code $find\n";

CGI Example

Network

1. Request server/http://pc89075.cse.cuhk.edu/

vc_index.html

Web Server(Web Professional)

Oracle 8

Database

Documents

Disk

Scripts

HTML formvc_ index.html

.... ....

Querytemplate+Code

login.pl

Learner/browser

2. Web Page vc_index.html

3. Action="login.pl "

/input login data4. Result Page

formrequestedby learner

2

passing CGI strings toscript and activate it3

query the databaseand get the results

change the results to HTML format

4

HTML and Perl files<html><head>... </head> <body>...

<form method="POST" action="/cgi-vc/login_2.pl"><input type="password" name="password">... </form></html>

read (STDIN, $login_raw, $ENV{'CONTENT_LENGTH'});%logindata=split (/[&=]/, $login_raw);foreach (keys %logindata){ $logindata{$_}=~s/%([\dA-Fa-f]{2})/chr(hex $1)/ge; $logindata{$_}=~s/\+/ /g;} $logid=$logindata{'login'};$passwd=$logindata{'password'};...

print "Content-type: text/html\n\n";print "<html><body>\n";...


Perl tutorial:Robert's Perl Tutorial

http://www.netcat.co.uk/rob/perl/win32perltut.html

Ten Perl Myths

http://www.perl.com/pub

ActiveSate Tool Corp.

http://www.activestate.com


Perl Editor:Pete's Place

http://www.petes-place.com/

Resources:CPAN Module documentation

http://theoryx5.uwinnipeq.ca/CPAN/

Matt's Script Archive

http://www.worldwidemart.com/scripts/

The End

CGI programming using Perl

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