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The key to this is carefully defining what you mean by a word. Once you've created your definition, use the special character types to create your regular expression:
/\S+/ // everything that isn't whitespace /[A-Z'-]+/i // all upper and lowercase letters, apostrophes, and hyphens
The simple question "what is a word?" is surprisingly complicated. While the Perl compatible regular expressions have a built-in word character type, specified by \w, it's important to understand exactly how PHP defines a word. Otherwise, your results may not be what you expect.
Normally, because it comes directly from Perl's definition of a word, \w encompasses all letters, digits, and underscores; this means a_z is a word, but the email address [email protected] is not.
In this recipe, we only consider English words, but other languages use different alphabets. Because Perl-compatible regular expressions use the current locale to define its settings, altering the locale can switch the definition of a letter, which then redefines the meaning of a word.
To combat this, you may want to explicitly enumerate the characters belonging to your words inside a character class. To add a nonstandard character, use \ddd , where ddd is a character's octal code.
Recipe 16.3 for information about setting locales.
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| 13.2. Switching From ereg to preg |  | 13.4. Finding the nth Occurrence of a Match |
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