This article originally appeared in the July 2002 issue of the Dæmon News Online Magazine. This is a cleaned-up version of the article with minor style edits and made it HTML5 compliant; else, the content has not been changed.
Authors: Rasmus Lerdorf & Kevin Tatroe with Bob Kaehms and Rick McGredy
Publisher: O'Reilly & Associates, Inc.
PHP is one of the most used scripting languages that is capable of running on multiple platforms, operating systems and web servers (FreeBSD/i386, Solaris/SPARC, Mac OS X, Windows + IIS, etc.) One of the many reasons why PHP has become so popular (excluding the fact that it is Open Sourced) is that it is capable of doing many things that Perl can do, but with a more friendly syntax while still being quite extensible. Learning how to write PHP code using the available PHP Manual is one of the popular options; however, the manual isn't too friendly to those who are new to programming or scripting languages: some of the sections in the manual are not complete and others do not provide enough examples or warnings on things that can trip up someone new to PHP. O'Reilly has published a book on PHP4 for those who want to get started in PHP programming, as well as hints on how to write relatively secure and stable applications.
In this book review, I will be giving a detailed overview of "Programming PHP" and will provide any critiques and additional comments that you can take into consideration when deciding to purchase the book. The book itself has 524 pages and is bound in the usual O'Reilly form factor and style; the size of the book is about right if you were going to be carrying it around in a backpack or a laptop bag without breaking your shoulders. The book is organized into fifteen chapters and two appendices, where the two appendices provide a basic PHP function list/reference and an extensions reference. Below is a brief table of contents contained in the book.
The first chapter introduces the PHP scripting language to the reader, a brief history of PHP
(including the text from the PHP release announcements for versions 1.0, 2.0, a.k.a. PHP/FI, and
3.0), installing PHP along with the Apache web server from the source tarballs (sorry, no
installation notes on installing PHP and Apache from BSD ports even though the platform listed in
the configure script output shows "
FreeBSD 4.2"), and finally some sample
scripts used in conjunction with a web server or as a shell script. The chapter does not cover all
php.ini configuration options; instead, it provides a link to the proper page in
the PHP Manual.
The next five chapters in the book (two through six) cover the very core of the PHP scripting language including: code syntax, style and structure, data types, operators (arithmetic, logical or bitwise), including files, functions, strings, POSIX and Perl regular expressions, arrays (which alone takes up about a third of chapter four), and objects. Each chapter provides sufficient examples to help explain the uses of the many different pieces of PHP, but doesn't overwhelm the reader with fluff nor is as terse as some documentation (if there are any). Unfortunately, working with Unicode strings are not really covered in any of these five chapters or even in the rest of the book. I think that covering a portion of handling Unicode strings should be included as more and more sites and applications are required to deal with multiple languages, primarily those that require multi-byte characters to represent all of the symbols in a particular language or written language style.
Chapters seven and eight cover topics that would be used by PHP programmers when building websites with
PHP. Chapter seven goes over functions and features used by almost all PHP based web sites such as
reading server variables, handling forms and utilizing cookies and sessions to maintain state. The
chapter briefly covers using the
header function to set content types, handle redirections,
page expiration (quite handy when dealing with proxy servers) and authentication. Even though the
authors cover the many uses of the
header function, one use was not covered and I think it
should be, sending a response code of 404, and building a semi-smart "Page Not Found" that
provides a link back to the referrer and maybe suggest a link to the visitor.
The next chapter focuses on setting up and using database connections by using the PEAR DB library
(rather than the specific database extension functions available and documented in the PHP Manual). The
examples provided in the chapter use a MySQL database server, though almost all of the examples would
also be valid for those who connect to a PostgreSQL database server. For those who are not familiar
with SQL queries and database tables, the chapter covers the most basic query statements (i.e.:
update) as well as creating and using tables. To combine
the items covered in the chapter, the authors include a web application that allow users to create
and maintain a business directory listing.
After the book covers the core of PHP in the last set of chapters, the authors cover some topics that may or may not be used in everyday web sites or applications. Chapter nine covers creating basic images using the GD library; ten covers creating PDF files along with basic text formatting, embedding images, notes and other files. One use of the GD library and PHP that was not included in chapter nine is the creation of basic graphs and charts, which are becoming more popular among managers. The eleventh chapter goes over creating XML files, handling XML files with and without using XSLT, using XML-RPC to create web services by pulling data from other web servers, and parsing Rich Site Summary (RSS) documents. The XML chapter does not cover the creation of a Document Type Definition (also known as DTD) or validating DTD, XML and XSLT files as that topic would (and does) fill up an entire book.
In chapter 12, the authors go over a topic that all PHP programmers should keep in mind while writing
PHP code: making sure that the code is as "secure" as possible. Earlier versions of PHP4
would allow the programmer to reference a query string or form variable by just using
var is the name of a query string and/or a form variable. PHP 4.20 and later disables
register_globals option (it can still be enabled in php.ini) by default. This can lead
to tainting of data if additional checks are not made. The chapter not only covers a way to make sure
that data is not being tainted, as well as dealing with file names, paths and permissions, and the
evils of allowing arbitrary PHP code and shell commands from being executed (but no mention of the
evils of allowing users to run arbitrary SQL queries on a database, which is a huge no-no).
The next chapter in the book, thirteen, goes through topics like using templates to possibly reduce
the number of hand written HTML pages, buffering or compressing the output, working with error handling,
benchmarking the web server using the Apache
ab program and inserting timers to find slow
points in your PHP application. Also included in the chapter are some simple tips to increase the
application's performance, as well other techniques to lower response time by using Squid to act as a
caching server along with load balancing web and database servers. The authors do not provide a whole
of lot detail on the last set of items as setting up caching servers and load balancing multiple
servers can get quite complicated and involve solutions outside of the scope of PHP.
Chapter fourteen is the only chapter in the book that is not geared for those who are just learning PHP and/or do not have C programming experience as the chapter is on writing C extensions to PHP. The chapter provides the basic steps for preparing, coding, and compiling both an extension that ROT13's a string; also covered is how to read in and return values, working with arrays, objects, references and variables using the structures provided in Zend and the Server Abstraction APIs. The pace of the chapter is a bit fast for those who only have a little experience in C (like me) but it should be an easy read for those who live and breathe C.
The last chapter in the book talks about using PHP within a Windows environment. On the web server side, the authors only cover using PHP with Personal Web Server and Apache under Windows 98, but does not cover how to get PHP to work with Internet Information Server (IIS) under Windows NT/2000. By not covering IIS, the authors miss out on a sizeable chunk of the readers who are required to work within Windows (for those who want to use PHP with IIS, you will probably find the specific section within the PHP Manual to be a decent starting point.) The chapter continues with tips that focus on writing code that is capable of running on both Windows and Unix, a brief discussion on using COM to write data out to a Word document, and using ODBC to connect to Windows-specific data sources like Access and Excel (but no information about connecting to a server running Microsoft SQL Server).
The first appendix in the book provides an alphabetically sorted function list (only functions that
are in the base PHP build are included, functions from any extensions that would be enabled via
configure are included) where each function includes the syntax and return value type (in
the form of
dataType functionName (dataType argument ...)), what the function does and
returns, and some include a list of valid values or modes. The descriptions of the functions are not
as detailed as the ones found in the PHP Manual, but it should be used as a quick reference rather
than a tutorial or training document.
Appendix B covers extensions that are available during the
configure phase of
building/installing PHP, including a brief description of what the extension provides, the dependant
libraries required to build that extension, and the
configure script option to enable that
extension. The authors refer the reader to the PHP website for more information about the dependant
libraries and other information regarding the extensions.
The book does a nice job of covering the basic concepts of programming in PHP as well as providing some insight and items to look out for to help teach those starting out in PHP how to write decent PHP code. For those who have quite a bit of PHP experience under his/her belt, the function reference in Appendix A along with the security chapter might be of use as a reference point. Those who are looking into writing PHP extensions and have quite a bit of experience in C programming may find the chapter on writing extensions (chapter fourteen) to be quite informative. There are some places where the book could be improved in the second edition:
I think that "Programming PHP" would provide a perfect complement to the PHP Manual for those who are looking into learning PHP as well as those who are fairly experienced in PHP. The "PHP Pocket Reference" (though it is a bit dated) may be a better choice for those well versed in PHP, are looking for a quick way to lookup function argument lists and don't wish to carry around a larger book.
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