Variables and Constants
Now that you know the basics of creating a PHP program, it’s time to learn about all the things a program can do. Essentially, all programs exchange and manipulate data. For example, the information from a Web site’s feedback form might be collected and sent via e-mail to the Webmaster. The data from the form would be stored in variables, which could then be used to send the form data in an e-mail.
Thus, you have seen one basic use for variables and constants. Any data that a program works with is stored in variables and constants. So, as we explore the way your program will work with data in this chapter and the chapters ahead, we’ll start with variables and constants, the storage units for all data.
This chapter teaches you the following:
How to declare variables and constants
Naming techniques
Types and type casting
Scope
References