PHP Tutorial

What Does PHP Do?

PHP does anything you want, except sit on its head and spin. Actually, with a little on-the-fly image manipulation and Dynamic HTML, it could probably do that, too.

According to the PHP manual, "The goal of the language is to allow Web developers to write dynamically generated pages quickly."

Here are some common uses of PHP:

Perform system functions: create, open, read from, write to, and close files on your system; execute system commands; create directories; and modify permissions.
Gather data from forms: save the data to a file, send data via e-mail, return manipulated data to the user.
Access databases and generate content on-the-fly, or create a Web interface for adding, deleting, and modifying elements within your database.
Set cookies and access cookie variables.
Start sessions and use session variables and objects.
Use PHP user authentication to restrict access to sections of your Web site.
Create images on-the-fly.
Encrypt data.

These are just everyday uses. PHP includes support for Java, Java Servlets, XML, and a myriad of other higher-level functions. The possibilities are endless.

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Better Th an Its Alternatives

In previous years, skeptics may have asked, Why should I learn PHP? Today, PHP's popularity is enough to generate interest in learning it. PHP is a standard feature offered by most Web hosting companies. However, it is interesting to understand.

Why so many people choose PHP over alternatives.

The short answer is that PHP is better. PHP is faster to code and faster to execute. The same PHP code runs unaltered on different Web servers and different operating systems. Additionally, functionality that is standard with PHP is an add-on in other environments. A more detailed argument follows.

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Works with the Web Server

The normal process a Web server goes through to deliver a page to a browser is as follows. It all begins when a browser makes a request for a Web page. Based on the URL, the browser resolves the address of the Web server, identifies the page it would like, and gives any other information the Web server may need. Some of this information is about the browser itself, like its name (Mozilla), its version (4.08), or the operating system (Linux). Other information given the Web server could include text the user typed into form fields.

If the request is for an HTML file, the Web server will simply find the file, tell the browser to expect some HTML text, and then send the contents of the file. The browser gets the contents and begins rendering the page based on the HTML code. If you have been programming HTML for any length of time, this will be clear to you.

When a PHP page is requested, it is processed exactly like a CGI, at least to the extent that the script is not simply sent to the browser. It is first passed through the PHP engine, which gives the Web server HTML text.

What Does PHP Do?

Better Th an Its Alternatives

Works with the Web Server

PHP Introduction

PHP Basic Development

PHP Control Structures

PHP Functions

PHP Arrays

PHP File System

Working With PHP Forms

PHP Classes And Objects

Introduction To Database

PHP Cookies

PHP Session

Computer SMS