ECMM6018 Enterprise Networking For Electronic Commerce Tutorial 5 Server Side Scripting Perl

What is it Server Side Language Cgi application resides in the /cgi-bin directory #! /opt/bin/perl Use CGI qw(:standard) ASP, JSP

Variable Types in Perl Scalar variable : Scalar variables used to contain strings, integer Numbers and floating point numbers (decimals) e.g. $varname Indexed array: A variable that can store different scalar values,e.g. numbers, decimals accessed $arrayname[i] Associative array: elements of an associative array are referred to as "key" and "value" pairs e.g. %array accessed $array{key} = pair Variable names should be restricted to just letters of the alphabet, i.e. leave out characters such as #, $, %, ^, &, *, (, ), ~

Mathematical Operators + Addition - Subtraction * Multiplication / Division ++ Adds one to the value on the left, i.e. j++, j=j+1 -- Subtracts one from the value on the left j--, j= j-1

Assignment Operators = Assigns what is on the right side to what is on the left e.g. a=3 += Adds the value of the right side to the left side and makes the variable on the left equal to it. e.g. a +=3, a=a+3 -= Subtracts the value of the right side to the left side and makes the variable on the left equal to it. e.g. a-=3, a=a-3

Comparison Operators < > <= >= == eq != Ne =~

Conditional Statement If If – Else If (condition) { statement } e.g. if ($a!=5) { print “Answer is not 5\n”; }

Conditional Statement If-Else If (condition) statement Else statement e.g. if ($a!=5) { print “Answer is not 5\n”; } else print “Answer is 5\n”;

Conditional Statement if ($stuff < 5) { print “short!\n"; } elsif ($stuff >= 6) { print “tall!\n"; } else { print “in between\n"; }

Looping While For Foreach

While Statement while (condition) { code to be executed } e.g. while ($stuff <6) { print “$stuff\n”; $stuff++; }

For Statement for (initialization; test condition; increment) { code to be executed } for ($i = 0; $i <= $#stuff; $i++) { print "$stuff[$i]"; }

For Each Statement foreach $slotspace { print "$slotspace"; } foreach $slotname (keys (%stuff)) { print "$stuff{$slotname}"; }