ECMM6018 ECMM6018 Enterprise Networking For Electronic Enterprise Networking For Electronic

CommerceCommerceTutorial 5Tutorial 5

Server Side Scripting

Perl

What is itWhat 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 PerlVariable 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

e.g. @arrayname

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 OperatorsMathematical 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 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 OperatorsComparison Operators

< > <= >= == eq != Ne =~

Conditional StatementConditional Statement

If If – Else

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

Conditional StatementConditional 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 StatementConditional Statement

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

LoopingLooping

WhileForForeach

While StatementWhile Statement

while (condition) { code to be executed }

e.g. while ($stuff <6) { print “$stuff\n”; $stuff++; }

For StatementFor Statement

for (initialization; test condition; increment)

{

code to be executed

}

for ($i = 0; $i <= $#stuff; $i++)

{

print "$stuff[$i]";

}

For EachFor Each Statement Statement

foreach $slotspace (@stuff)

{

print "$slotspace";

}

foreach $slotname (keys (%stuff)) { print "$stuff{$slotname}"; }