PHP Developer's Guide

The remarkable volume of information which has moved to the Web over the last few years, and the complexity of delivering it dynamically to Web users, have resulted in the increased popularity of programming languages designed specifically for delivery of Web content.

If you read the 'PHP Hypertext Preprocessor' column, you might have been wondering about some of the peculiarities of string handling with PHP. Strings, simply, consist of one or more characters in sequence. In PHP, $s = "string" creates a string variable 's' that contains the string "string".

In this column we look at writing data to files in a structured format and how to read it back in that format.

There are two stages to receiving data from Web users: the first is to provide an interface to interact with, and the second is to retrieve this information. The most common way to do this is through the Common Gateway Interface (CGI), supported by PHP.

The previous column, 'Collecting user data' looked at how to accept data from basic HTML forms and store then in a structured format in a file. As this is such an important topic for those looking to become skilled in PHP development, we will revisit it here. Over the past few columns we have been building up to a complete and useful project powered by PHP: a basic address book which can accept new data and search through existing data.

We have looked at storing address book entries submitted by users. The other requirement of an address book is to be able to locate an address. Now we will look at parsing address book entries and matching a user-supplied string: a search engine.

We have looked at building a basic address book database system. Address Book 1 stored its data in a flat file format - that is, plain text. The problem with storing data like this is that it is inefficient to search the entire address book line by line to locate a particular entry. Moreover, to search multiple fields of an entry - such as last name and suburb - required additional code.

In the last column we introduced the use of embedded databases within PHP via the Database Abstract (DBA) Layer. Now, we will re-implement Address Book 1 (AB1) using this superior technology.

This column will look at modifying 'Address book in PHP revisited's' AB2 code to allow searching of multiple data fields.

This column has been looking at ways to simplify the development of a database-driven Web-based address book. Now we look at a complete solution: the PostgreSQL Object Relational Database Management System (ORDBMS).

We have looked extensively at interacting with the PostgreSQL relational database; now we look at integrating this into our ongoing project - a database-driven address book. First, we will have to create a table in the PostgreSQL database where we can store the data. This is done with the following query:

Security of applications is one of the most important aspects of programming today - and one of the most overlooked and misunderstood. Now we will look at different security problems that face PHP developers and techniques to solve them.

As well as being great for generating textual content dynamically, PHP is also useful for dynamically creating images. Using a special PHP extension, we'll explore the possibilities of image creation in this column over the next few columns.

The focus of object orientation is the logical grouping of related variables into a generic variable - an object. Before you can create an object, however, you must create a class. A class is a template for an object. The following class, Vehicle, is designed to describe attributes of 'any' vehicle.

The PHP Extension and Application Repository (PEAR) is an open source structured library of packages for PHP developers. These packages provide routines which solve problems PHP developers regularly face: sending structured e-mail (such as an HTML attachment), interacting with different databases from a single script, error handling, recovery and logging.