Perl and PHP Cross Reference Guide

With Perl, you simply copy your files to a web server that is capable of running Perl pages.

With PHP, you simply copy your files to a web server that is capable of running PHP pages.

Many developers just use a text editor but you have to be careful when developing on Windows and deploying to Unix/Linix. Some Windows text editors including Notepad, and Microsoft Expression Web save text files in UTF-8 which is not compatible with Unix/Linux.

There are many Perl editors available including ActivePerl Pro Studio, and the free Perl Express. I usually use Perl Express.

Quick Start: Install Perl to IIS or Apache, install Perl Express then configure to use Perl, then install MySQL. For IIS 7, you will likely have to configure Hangler Mappings and add %s %s.

Many developers just use a text editor. There are many PHP editors available including phpDesigner, and Delphi for PHP.

.pl is the traditonal default extension for Perl although some developers will change the default extension in an effort to add an additional security level and .cgi is still popular as a Perl associated extension as well as .plex and .aspl.

• .pl - Perl
• .cgi - Common Gateway Interface
• .plex - Perl Executable
• .aspl - Active Server Perl

.php is the default extension for PHP although some developers will change the default extension in an effort to add an additional security level. If your code is tied to a particular version of PHP then some developers at the major PHP version number to the extension as in .php3, .php4, .php5, etc. 

.phtml is also sometimes used especially for files that contain both HTML and Perl code.

Language Overview: Perl is a stable, cross platform programming language.

Target Platforms: Perl is most suitable for creating websites targeting any browser (any web server with the Perl module installed).

History: PERL is an acronym for Practical Extraction and Report Language. It is used for mission critical projects in the public and private sectors. Perl is Open Source software, licensed under its Artistic License, or the GNU General Public License (GPL). Perl was created in 1987 by Larry Wall.

PHP is a hybrid language with both traditional PHP and OOP features. PHP is widely-used general-purpose scripting language that is especially suited for web development and can be embedded into HTML. PHP has been used to create some amazing web content, particularly outstanding message boards.

Target Platforms: PHP is most suitable for creating websites targeting any browser (any web server with PHP installed).

No built-in report writer but because website development targets a client browser (a document interfaced GUI), a common solution is to simply output an HTML formatted page with black text and a white background (not much control but it does work for some situations).

No built-in report writer but because website development targets a client browser (a document interfaced GUI), a common solution is to simply output an HTML formatted page with black text and a white background (not much control but it does work for some situations).

Perl is case sensitive.

print "hello"; //This works.

Print "hello"; //This does not.

PHP is case sensitive with variable names but not with commands. Although commands are case incenstive, I prefer to use all lowercase because it's easy to type and that's what I see most PHP coders doing and I see it on PHP.Net.

echo "hello<br>";

ECHO "hello<br>";

Echo "hello<br>";

eCHo "hello<br>";

$fullname = "Mike Prestwood"; //These are two...

$FullName = "Wes Peterson";   //separate varialbes.

In Perl, you create the entire HTML page within your .PL script file using print commands.

For Perl, PHP, JavaScript, Java,and C++, I prefer to put the first { at the end of the first line of the code block as in this example because I see morePeal codeformatted that way.

$x = "Yes";

If ($x == "Yes") {
  print "Hello world";

  print "I am a Perl coder.";

}

In .PHP html pages, you embed PHP code between <?PHP and ?>.

For PHP, JavaScript, Java,and C++, I prefer to put the first { at the end of the first line of the code block as in the example above because I see morePHP codeformatted that way (and on PHP.Net).

PHP Alternative Syntax

Although I don't like to use it, PHP offers an alternative syntax for if, while, for, foreach, and switch. These code blocks are surrounded by statement ending keywords that all use End with camel caps such as endif, endwhile, endfor, endforeach,and endswitch.

<?PHP

$x = "Yes";

//Simple if

If ($x == "Yes")
  echo "hello world";

//If with a block of code.

If ($x == "Yes") {
  echo "Hello world";

  echo "I am a PHP coder!";

}

?>

Commenting Code
Perl uses # for single line comments and Perl does NOT have a multiple line comment.

Compiler Directives (A special comment.)

Perl also uses compiler directives embedded in comments with #! as in:

#!/usr/local/bin/perl -w

#This is a comment in Perl.

Commenting Code
Use the multi-line to comment out large blocks of code and to write multiple line comments.

#This is a comment in PHP.

//This is too!
 

/*

This is a multi-line

comment.

*/

In Perl, you declare constants using the use constant keywords:

use constant CONST_NAME => "Value";

Constants in Perl are case sensitive. A common standard in Perl is to use all-uppercase letters, with underscores to separate words within the name.

use constant FULL_NAME => 'Mike Prestwood';
use constant AGE => 38;

print "Your name is " . FULL_NAME . ".<br>";
print "You are " . AGE . ".<br>";

In PHP, you declare constants using the define keyword:

define("CONST_NAME", "Value");

Constants in PHP are case sensitive. A common standard in PHP is to use all-uppercase letters, with underscores to separate words within the name.

define('FULL_NAME', 'Mike Prestwood');
define("AGE", 25);

echo "Your name is " . FULL_NAME . ".";
echo "You are " . AGE . ".";

 PHP Constants (define)

String literals are quoted as in "Prestwood". If you need to embed a quote use a slash in front of the quote as in \".

To specify a floating point literal between 1 and -1, you can preceed the decimal with a 0 or not (both work). In other words, preceding and following decimals are allowed (both .1 and 0.1). Trailing decimals are also allowed (1, 1., and 1.0 are all equivalent and allowed).

print "Hello";

print "Hello \"Mike\".";

#Does Perl evaluate this simple

#floating point math correctly? No! 

if ((.1 + .1 + .1) == .3) {
  print("Correct");
} else {
  print("Not correct");
}

 Perl Literals (quote)

In PHP you can use quotes, or apostrophes as in "Prestwood", and 'Prestwood' for string literals. Use a slash in front of a quote or apostrophe to embed same type as in \' and \".

To specify a floating point literal between 1 and -1, you can preceed the decimal with a 0 or not (both work). In other words, preceding and following decimals are allowed (both .1 and 0.1). Trailing decimals are also allowed (1, 1., and 1.0 are all equivalent and allowed).

echo "Mike's drums are over there.<br>";
echo 'Mike said, "hi!"<br>';

//Does PHP evaluate this simple

//floating point math correctly? No! 

If ((.1 + .1 + .1) == .3) {
 Echo "Correct";
} Else {
 Echo "Not correct";
}

 PHP Literals (quote or apostrophe)

Perl is a loosely typed language with only three types of variables: scalars, arrays, and hashes. Use $ for a scalar variable, @ for an array, or % for a hash (an associative array).

The scalar variable type is used for any type of simple data such as strings, integers, and numbers. In Perl, you identify and use a variable with a $ even within strings.

#!/usr/local/bin/perl -w

 
print("Content-type: text/html\n\n");

$fullname = 'Mike Prestwood';
$Age = 38;
$Weight = 162.4;

 

print "Your name is $fullname.
";
print "You are $Age and weigh $Weight.
";

 Perl Variables ($x = 0;)

PHP is a loosely typed language. No variable types in PHP. Declaring and using variables are a bit different than in other languages. In PHP, you identify and use a variable with a $ even within strings!

You assign by reference with & as in &$MyVar.

$fullname = 'Mike Prestwood';
$FullName = 'Wes Peterson';   //This is a different variable!
$Age = 38;
$Weight = 162.4;

 

echo "Your name is $fullname.
";
echo "You are $Age and weigh $Weight.
";

 PHP Variables ($x = 0;)

Perl uses subs and parameters are referenced in a special array. All arguments passed to a subroutine are stored in a special @_ array. To retrieve the arguments, you have to look inside the array and extract them.

sub sayHello {
 my ($pName) = $_[0];
 print("Hello $pName!");
}

sub add {
 my ($p1) = $_[0];
 my ($p2) = $_[1];
 return $p1 + $p2;
}

 Perl Custom Routines (sub)

PHP uses functions and loosely typed parameters. Function definitions can come before or after their usage so my preference when mixing PHP in with a mostly HTML page is to put the functions after the </html> tag.

function sayHello($pName) {
 echo "Hello " . $pName . "<br>";
}

function add($p1, $p2) {
 return $p1 + $p2;
}

 PHP Custom Function (function)

Perl

• Operator - Yes
• Method -

 Perl Overloading

PHP

• Operator - No.
• Method -

 PHP Overloading

Declare associative array with initial known values. You can also add to associative array. (You can just assign values without ever declaring it too!)

$prices = array( 'Tires'=>100, 'Spark Plugs'=>4 );
$prices['Oil'] = 10;

echo "Tires=" . $prices['Tires'] . "<br>";
echo "Oil=" . $prices['Oil'] . "<br>";

 PHP Associative Array

Perl supports both pointers and references.

PHP supports references which allow you to refer to the value of a variable but PHP does not support true developer defined pointers. You cannot get and use the address of a variable.

However, you can still do inexpensive assignments by assigning by reference.

Notice Perl is different from most other languages in it's spelling of elsif (else is not spelled correctly).

$x = 8;

if ($x == 10) {
 print "X is 10.";
} elsif ($x < 10) {
 print "X is less than 10.";
} else {
 print "X must be greater than 10.";
}

The PHP if statement consists of using if, elseif, and else.

$x = 8;

if ($x == 10) {
 echo "x is 10.";  
} elseif ($x < 10) {
 echo "x is less than 10.";
} else {
 echo "x must be greater than 10.";  
};

Perl assignment operators:

$FullName = "Randy Spitz";
$Age = 38;

PHP uses = for it's assignment operator.

$fullname = "Randy Spitz";

$age = 38;

Common comparison operators:

Perl also offers additional string comparison operators:

#Does Perl evaluate the math correctly? No!

if ((.1 + .1 + .1) == .3) {
  print("Correct<br>");
} else {
  print("Not correct<br>");
}

Common comparison operators:

PHP 4 and above also offers === for indentical (equal plus same type) and !== for not identical (not equal or not same type).

//Does PHP evaluate the math correctly? No!

if (.1 + .1 + .1 == .3) {
  echo "correct";
}
else {
  echo "not correct";
}

Perl logical operators:

#Given expressions a, b, c, and d:

if !((a && b) && (c || d)) {

  #Do something.

}

PHP logical operators:

#Given expressions a, b, c, and d:

if !((a && b) && (c || d)) {

  #Do something.

};

Perl uses a period (.) known as a dot to concatenate strings.

$fname = "Mike";
$lname = "Prestwood";

$fullname = $fname . $lname . "
";

print "My name is " . "Mike.
";

PHP uses a period (.) known as a dot to concatenate strings.

$fname = "Mike";
$lname = "Prestwood";

$fullname = $fname . $lname . "
";

echo "My name is " . "Mike.
";

 PHP String Concatenation (.)

An operation with only one operand (a single input). The following are the Perl unary operators: !, -, ~, +, \, &, and *.

• ! performs logical negation which is "not"
• - performs arithmetic negation if the operand is numeric.
• ~ performs bitwise negation, that is 1's complement.
• + has no semantic effect whatsoever, even on strings.
• \ creates a reference to whatsoever follows.
• & Address of operator.
• * Dereference address operator.

 Perl Unary Operators

A unary operator operates on only one value.

PHP Examples:

• ! negation operator
• ++ increment operator
• -- decrement operator

 PHP Unary Operators