PHP Cookbook, 2nd Edition

Chapter 1. Strings

Introduction

Strings in PHP are sequences of bytes, such as “We hold these truths to be self-evident” or “Once upon a time” or even “111211211.” When you read data from a file or output it to a web browser, your data are represented as strings.

PHP strings are binary-safe (i.e., they can contain null bytes) and can grow and shrink on demand. Their size is limited only by the amount of memory that is available to PHP.

Warning

Usually, PHP strings are ASCII strings. You must do extra work to handle non-ASCII data like UTF-8 or other multibyte character encodings, see Chapter 19.

Similar in form and behavior to Perl and the Unix shell, strings can be initialized in three ways: with single quotes, with double quotes , and with the “here document” (heredoc) format. With single-quoted strings, the only special characters you need to escape inside a string are backslash and the single quote itself. Example 1-1 shows four single-quoted strings.

Example 1-1. Single-quoted strings

print 'I have gone to the store.';
print 'I\'ve gone to the store.';
print 'Would you pay $1.75 for 8 ounces of tap water?';
print 'In double-quoted strings, newline is represented by \n';

Example 1-1 prints:

I have gone to the store.
I've gone to the store.
Would you pay $1.75 for 8 ounces of tap water?
In double-quoted strings, newline is represented by \n

Because PHP doesn’t check for variable interpolation or almost any escape sequences in single-quoted strings, defining strings this way is straightforward ...