PHP
Introduction
PHP started out as a small open source project that
evolved as more and more people found out how useful it was. Rasmus Lerdorf
unleashed the first version of PHP way back in 1994.
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PHP is a recursive acronym for
"PHP: Hypertext Preprocessor".
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PHP is a server side scripting language
that is embedded in HTML. It is used to manage dynamic content, databases,
session tracking, even build entire e-commerce sites.
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It is integrated with a number of
popular databases, including MySQL, PostgreSQL, Oracle, Sybase, Informix, and
Microsoft SQL Server.
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PHP is pleasingly zippy in its
execution, especially when compiled as an Apache module on the Unix side. The
MySQL server, once started, executes even very complex queries with huge result
sets in record-setting time.
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PHP supports a large number of major
protocols such as POP3, IMAP, and LDAP. PHP4 added support for Java and
distributed object architectures (COM and CORBA), making n-tier development a
possibility for the first time.
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PHP is forgiving: PHP language tries to
be as forgiving as possible.
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PHP Syntax is C-Like.
Common uses of
PHP
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PHP performs system functions, i.e.
from files on a system it can create, open, read, write, and close them.
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PHP can handle forms, i.e. gather data
from files, save data to a file, thru email you can send data, return data to
the user.
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You add, delete, modify elements within
your database thru PHP.
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Access cookies variables and set
cookies.
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Using PHP, you can restrict users to
access some pages of your website.
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It can encrypt data.
Characteristics
of PHP
Five important characteristics make PHP's practical
nature possible −
"Hello
World" Script in PHP
To get a feel for PHP, first start with simple PHP
scripts. Since "Hello, World!" is an essential example, first we will
create a friendly little "Hello, World!" script.
As mentioned earlier, PHP is embedded in HTML. That
means that in amongst your normal HTML (or XHTML if you're cutting-edge) you'll
have PHP statements like this −
<html>
<head>
<title>Hello World</title>
</head>
<body>
<?php
echo "Hello, World!";?>
</body>
</html>
It will produce following result −
Hello,
World!
If you examine the HTML output of the above
example, you'll notice that the PHP code is not present in the file sent from
the server to your Web browser. All of the PHP present in the Web page is
processed and stripped from the page; the only thing returned to the client
from the Web server is pure HTML output.
All PHP code must be included inside one of the
three special markup tags ate are recognised by the PHP Parser.
<?php PHP code goes here ?>
<? PHP code goes here ?>
<script language="php"> PHP code goes here </script>
A most common tag is the <?php...?> and we
will also use the same tag in our tutorial.
From the next chapter we will start with PHP
Environment Setup on your machine and then we will dig out almost all concepts
related to PHP to make you comfortable with the PHP language.