Beginning PHP 5.3

Chapter 5. Strings

You briefly looked at the concept of strings back in Chapter 3. In programming-speak, a string is simply a sequence of characters. For instance, the values "hello", "how are you?", "123", and "!@#$%" are all valid string values.

Fundamentally, the Web is based on string data. HTML and XHTML pages consist of strings of plain text, as does HTTP header information (more on this in Chapter 16) and, of course, URLs. As you'd imagine, this means that Web programming languages such as PHP are particularly geared toward working with strings. Indeed, PHP has nearly 100 different functions that are directly concerned with manipulating strings.

For example, you can use PHP's string functions to:

• Search for text within a string

• Replace some text within a string with another string of text

• Format strings so that they're easier to read or work with

• Encode and decode strings using various popular encoding formats

On top of all that, you can also work with strings using regular expressions (which you learn about in Chapter 18).

In this chapter you look at the basics of strings in PHP — how to create string values and variables, and how to access characters within strings. You then explore PHP's string functions. The chapter doesn't aim to cover every single string function in PHP; the subject could fill a whole book on its own. Instead, you get to learn about the most useful (and commonly used) functions that you're likely to need in everyday situations.

If you want the full list ...