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Character class abbreviations allow you to match any of a set of characters without too much hassle. One way to do this is to put the set of characters you want to match from within []. For instance [0123456789] would allow you to match any of those numbers. This can be kind of cumbersome. You can also negate a character class by placing a caret at the front of it. For instance [^0123456789] matches anything that is not a number. You shouldn't be surprised that Perl makes your life much easier by defining some character class a bbreviations. These are alphanumeric characters preceded by a backslash. Perl allows you to match any number with a \d in your regular expression.

Now for a quick word about metacharacters. Metacharacters are characters that have special meaning within regular expressions. Therefore if you put them into a regular expression they won't match literally. Unless you precede the metacharacter with a \. The metacharacters are \|()$^.?* Now for a quick word about each of them do before we return to character class abbreviations.
Metacharacter(s)Meaning
.Matches any character besides newline
()Used for grouping characters
[]Used for defining character classes
|Used for or in regular expression
\Denotes the beginning of a character class abbreviation, or for the following metacharacter to be matched literally
*Quantifier matches 0 or more of the previous character or group of characters
?Makes a quantifier nongreedy
^Matches the beginning of a string (or line if /m is used)
$Matches the end of a string (or line if /m is used)


Now lets define some character classes

Character ClassMeaning
\ddigit or [0123456789]
\Dnondigit or [^0123456789]
\wword (alphanumeric) or [a-zA-Z_0-9]
\Wnonword
\bword boundary
\swhitespace character [ \t\r\n\f]
\Snon whitespace character


That's a lot of information to get a handle on. So lets check out pattern-matching examples

In reply to Character Class Abbreviations by root

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