Learning MySQL

Language Basics

This section is a short introduction to the basic syntax of PHP. If you’re familiar with high-level languages such as C, C++, Java, JavaScript, or Perl, then you’ll find PHP very easy to learn. PHP began its life as a simple, procedural language that was designed to be embedded into HTML pages, and that’s mostly what we focus on this chapter. More recently, it has become a full-fledged object oriented (OO) language that can be used for nonweb and cross-platform applications, including both scripts that run from the command-line and programs with graphical user interfaces (see the PHP-GTK web site, http://gtk.php.net). You’ll find pointers to comprehensive PHP resources in Resources” at the end of this chapter.

As discussed previously, PHP scripts are surrounded by the PHP start tag <?php and the PHP end tag ?>. You’ll sometimes see the start tag abbreviated to <?, but this conflicts with the XHTML standard and should be avoided. Statements in a script are terminated with a semicolon. Statements can be formatted for readability by including any amount of whitespace—such as space characters, tab characters,or blank lines—in a script.

Comments can be included in a PHP script using the following styles:

// One-line comment

#  Another one-line comment

/* A
multiple-line
comment */

Anything that appears after the // or #, or between the /* and */ characters, is ignored.

Variables are prefixed with a dollar sign ($) and variable names are case-sensitive. PHP has several variable ...