Programming Perl, 4th Edition

Classic Perl Character Class Shortcuts

Since the beginning, Perl has provided a number of character class shortcuts. These are listed in Table 5-11. All of them are backslashed alphabetic metasymbols, and, in each case, the uppercase version is the negation of the lowercase version.

These match much more than you might think, because they normally work on the full Unicode range not on ASCII alone (and for negated classes, even beyond Unicode). In any case, the normal meanings are a superset of the old ASCII or locale meanings. For explanations of the properties and the legacy POSIX forms, see POSIX-Style Character Classes later in this chapter. To keep the old ASCII meanings, you can always use re "/a" for that scope, or put a /a or two on an individual pattern.

Table 5-11. Classic character classes

Symbol	Meaning	Normal Property	/a Property	/a Enumerated	Legacy [:POSIX:]
\d	Digit	\p{X_POSIX_Digit}	\p{POSIX_Digit}	[0–9]	[:digit:]
\D	Nondigit	\P{X_POSIX_Digit}	\P{POSIX_Digit}	[^0–9]	[:^digit:]
\w	Word character	\p{X_POSIX_Word}	\p{POSIX_Word}	[_A–Za–z0–9]	[:word:]
\W	Non-(word character)	\P{X_POSIX_Word}	\P{POSIX_Word}	[^_A–Za–z0–9]	[:^word:]
\s	Whitespace	\p{X_Perl_Space}	\p{Perl_Space}	[\t\n\f\r ]	[:space:] [a]
\S	Nonwhitespace	\P{X_Perl_Space}	\P{Perl_Space}	[^\t\n\f\r ]	[:^space:]
\h	Horizontal whitespace character	\p{Horiz_Space}	\p{Horiz_Space}	Many	[:blank:]
\H	Non-(Horizontal whitespace character)	\P{Horiz_Space}	\P{Horiz_Space}	Many	[:^blank:]
\v	Vertical whitespace character	\p{Vert_Space}	\p{Vert_Space}	Many	—
\V	Non-(Vertical whitespace ...