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PHP : Getting Started : Introduction

Chapter1.Introduction

Table of Contents

What is PHP?
What can PHP do?

What is PHP?

PHP (recursive acronym for "PHP: Hypertext Preprocessor") is a widely-used Open Source general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.

Simple answer, but what does that mean? An example:

Example1.1.An introductory example

<html>
<head>
<title>Example</title>
</head>
<body>

<?php
echo "Hi, I'm a PHP script!";
?>

</body>
</html>


Notice how this is different from a script written in other languages like Perl or C -- instead of writing a program with lots of commands to output HTML, you write an HTML script with some embedded code to do something (in this case, output some text). The PHP code is enclosed in special start and end tags that allow you to jump into and out of "PHP mode".

What distinguishes PHP from something like client-side JavaScript is that the code is executed on the server. If you were to have a script similar to the above on your server, the client would receive the results of running that script, with no way of determining what the underlying code may be. You can even configure your web server to process all your HTML files with PHP, and then there's really no way that users can tell what you have up your sleeve.

The best things in using PHP are that it is extremely simple for a newcomer, but offers many advanced features for a professional programmer. Don't be afraid reading the long list of PHP's features. You can jump in, in a short time, and start writing simple scripts in a few hours.

Although PHP's development is focused on server-side scripting, you can do much more with it. Read on, and see more in the What can PHP do? section, or go right to the introductory tutorial if you are only interested in web programming.

Related Examples ( Source code ) » introduction


Code Examples / Notes » introduction

winks716

before html runs to show a webpage, php code runs first on web server.
so, when there lines as follow:
<table>
<tr>
<td>
 <?php
   echo "php runs first!";
 ?>
</td>
</tr>
</table>
the first step is to run php code, we get:
<table>
<tr>
<td>
php runs first
</td>
</tr>
</table>
then, code is sent to browser, and we see somthing~


george dot langley

"the code is executed on the server"
This is an important concept for the first-time PHP programmer to understand, so that when you get into string formatting later on, you understand the difference between formatting the on-screen content (as parsed by your browser) and formatting the HTML code (as returned by the server).
For example "/n" starts a new line in the HTML code, and its results are only seen if you look at the "source HTML". It is NOT the same as
!


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