perlrecharclass


DESCRIPTION
       The top level documentation about Perl regular expressions is found in
       perlre.

       This manual page discusses the syntax and use of character classes in
       Perl regular expressions.

       A character class is a way of denoting a set of characters in such a
       way that one character of the set is matched.  It's important to
       remember that: matching a character class consumes exactly one
       character in the source string. (The source string is the string the
       regular expression is matched against.)

       There are three types of character classes in Perl regular expressions:
       the dot, backslash sequences, and the form enclosed in square brackets.
       Keep in mind, though, that often the term "character class" is used to
       mean just the bracketed form.  Certainly, most Perl documentation does
       that.

   The dot
       The dot (or period), "." is probably the most used, and certainly the
       most well-known character class. By default, a dot matches any
       character, except for the newline. The default can be changed to add
       matching the newline by using the single line modifier: either for the
       entire regular expression with the "/s" modifier, or locally with
       "(?s)".  (The experimental "\N" backslash sequence, described below,
       matches any character except newline without regard to the single line
       modifier.)

       Here are some examples:

        "a"  =~  /./       # Match
        "."  =~  /./       # Match
        ""   =~  /./       # No match (dot has to match a character)
        "\n" =~  /./       # No match (dot does not match a newline)
        "\n" =~  /./s      # Match (global 'single line' modifier)
        "\n" =~  /(?s:.)/  # Match (local 'single line' modifier)
        "ab" =~  /^.$/     # No match (dot matches one character)

   Backslash sequences
       A backslash sequence is a sequence of characters, the first one of
       which is a backslash.  Perl ascribes special meaning to many such
       sequences, and some of these are character classes.  That is, they
       match a single character each, provided that the character belongs to
       the specific set of characters defined by the sequence.

       Here's a list of the backslash sequences that are character classes.
       They are discussed in more detail below.  (For the backslash sequences
       that aren't character classes, see perlrebackslash.)

        \d             Match a decimal digit character.
        \D             Match a non-decimal-digit character.
        \w             Match a "word" character.

       "\d" matches a single character considered to be a decimal digit.  If
       the "/a" modifier in effect, it matches [0-9].  Otherwise, it matches
       anything that is matched by "\p{Digit}", which includes [0-9].  (An
       unlikely possible exception is that under locale matching rules, the
       current locale might not have [0-9] matched by "\d", and/or might match
       other characters whose code point is less than 256.  Such a locale
       definition would be in violation of the C language standard, but Perl
       doesn't currently assume anything in regard to this.)

       What this means is that unless the "/a" modifier is in effect "\d" not
       only matches the digits '0' - '9', but also Arabic, Devanagari, and
       digits from other languages.  This may cause some confusion, and some
       security issues.

       Some digits that "\d" matches look like some of the [0-9] ones, but
       have different values.  For example, BENGALI DIGIT FOUR (U+09EA) looks
       very much like an ASCII DIGIT EIGHT (U+0038).  An application that is
       expecting only the ASCII digits might be misled, or if the match is
       "\d+", the matched string might contain a mixture of digits from
       different writing systems that look like they signify a number
       different than they actually do. "num()" in Unicode::UCD can be used to
       safely calculate the value, returning "undef" if the input string
       contains such a mixture.

       What "\p{Digit}" means (and hence "\d" except under the "/a" modifier)
       is "\p{General_Category=Decimal_Number}", or synonymously,
       "\p{General_Category=Digit}".  Starting with Unicode version 4.1, this
       is the same set of characters matched by "\p{Numeric_Type=Decimal}".
       But Unicode also has a different property with a similar name,
       "\p{Numeric_Type=Digit}", which matches a completely different set of
       characters.  These characters are things such as "CIRCLED DIGIT ONE" or
       subscripts, or are from writing systems that lack all ten digits.

       The design intent is for "\d" to exactly match the set of characters
       that can safely be used with "normal" big-endian positional decimal
       syntax, where, for example 123 means one 'hundred', plus two 'tens',
       plus three 'ones'.  This positional notation does not necessarily apply
       to characters that match the other type of "digit",
       "\p{Numeric_Type=Digit}", and so "\d" doesn't match them.

       In Unicode 5.2, the Tamil digits (U+0BE6 - U+0BEF) can also legally be
       used in old-style Tamil numbers in which they would appear no more than
       one in a row, separated by characters that mean "times 10", "times
       100", etc.  (See <http://www.unicode.org/notes/tn21>.)

       Any character not matched by "\d" is matched by "\D".

       Word characters

       A "\w" matches a single alphanumeric character (an alphabetic
       character, or a decimal digit) or a connecting punctuation character,
       such as an underscore ("_").  It does not match a whole word.  To match
       a whole word, use "\w+".  This isn't the same thing as matching an
               TILDE" and the modifier letters, which are generally used to
               add auxiliary markings to letters.

           For code points below 256 ...
               if locale rules are in effect ...
                   "\w" matches the platform's native underscore character
                   plus whatever the locale considers to be alphanumeric.

               if Unicode rules are in effect or if on an EBCDIC platform ...
                   "\w" matches exactly what "\p{Word}" matches.

               otherwise ...
                   "\w" matches [a-zA-Z0-9_].

       Which rules apply are determined as described in "Which character set
       modifier is in effect?" in perlre.

       There are a number of security issues with the full Unicode list of
       word characters.  See <http://unicode.org/reports/tr36>.

       Also, for a somewhat finer-grained set of characters that are in
       programming language identifiers beyond the ASCII range, you may wish
       to instead use the more customized Unicode properties, "ID_Start",
       ID_Continue", "XID_Start", and "XID_Continue".  See
       <http://unicode.org/reports/tr31>.

       Any character not matched by "\w" is matched by "\W".

       Whitespace

       "\s" matches any single character considered whitespace.

       If the "/a" modifier is in effect ...
           "\s" matches the 5 characters [\t\n\f\r ]; that is, the horizontal
           tab, the newline, the form feed, the carriage return, and the
           space.  (Note that it doesn't match the vertical tab, "\cK" on
           ASCII platforms.)

       otherwise ...
           For code points above 255 ...
               "\s" matches exactly the code points above 255 shown with an
               "s" column in the table below.

           For code points below 256 ...
               if locale rules are in effect ...
                   "\s" matches whatever the locale considers to be
                   whitespace.  Note that this is likely to include the
                   vertical space, unlike non-locale "\s" matching.

               if Unicode rules are in effect or if on an EBCDIC platform ...
                   "\s" matches exactly the characters shown with an "s"
                   column in the table below.

               otherwise ...

       "\v" matches any character considered vertical whitespace; this
       includes the carriage return and line feed characters (newline) plus
       several other characters, all listed in the table below.  "\V" matches
       any character not considered vertical whitespace.

       "\R" matches anything that can be considered a newline under Unicode
       rules. It's not a character class, as it can match a multi-character
       sequence. Therefore, it cannot be used inside a bracketed character
       class; use "\v" instead (vertical whitespace).  Details are discussed
       in perlrebackslash.

       Note that unlike "\s" (and "\d" and "\w"), "\h" and "\v" always match
       the same characters, without regard to other factors, such as whether
       the source string is in UTF-8 format.

       One might think that "\s" is equivalent to "[\h\v]". This is not true.
       For example, the vertical tab ("\x0b") is not matched by "\s", it is
       however considered vertical whitespace.

       The following table is a complete listing of characters matched by
       "\s", "\h" and "\v" as of Unicode 6.0.

       The first column gives the code point of the character (in hex format),
       the second column gives the (Unicode) name. The third column indicates
       by which class(es) the character is matched (assuming no locale or
       EBCDIC code page is in effect that changes the "\s" matching).

        0x00009        CHARACTER TABULATION   h s
        0x0000a              LINE FEED (LF)    vs
        0x0000b             LINE TABULATION    v
        0x0000c              FORM FEED (FF)    vs
        0x0000d        CARRIAGE RETURN (CR)    vs
        0x00020                       SPACE   h s
        0x00085             NEXT LINE (NEL)    vs  [1]
        0x000a0              NO-BREAK SPACE   h s  [1]
        0x01680            OGHAM SPACE MARK   h s
        0x0180e   MONGOLIAN VOWEL SEPARATOR   h s
        0x02000                     EN QUAD   h s
        0x02001                     EM QUAD   h s
        0x02002                    EN SPACE   h s
        0x02003                    EM SPACE   h s
        0x02004          THREE-PER-EM SPACE   h s
        0x02005           FOUR-PER-EM SPACE   h s
        0x02006            SIX-PER-EM SPACE   h s
        0x02007                FIGURE SPACE   h s
        0x02008           PUNCTUATION SPACE   h s
        0x02009                  THIN SPACE   h s
        0x0200a                  HAIR SPACE   h s
        0x02028              LINE SEPARATOR    vs
        0x02029         PARAGRAPH SEPARATOR    vs
        0x0202f       NARROW NO-BREAK SPACE   h s
        0x0205f   MEDIUM MATHEMATICAL SPACE   h s
        0x03000           IDEOGRAPHIC SPACE   h s

       means to match 3 non-newlines; "\N{5,}" means to match 5 or more non-
       newlines.  But if "{...}" is not a legal quantifier, it is presumed to
       be a named character.  See charnames for those.  For example, none of
       "\N{COLON}", "\N{4F}", and "\N{F4}" contain legal quantifiers, so Perl
       will try to find characters whose names are respectively "COLON", "4F",
       and "F4".

       Unicode Properties

       "\pP" and "\p{Prop}" are character classes to match characters that fit
       given Unicode properties.  One letter property names can be used in the
       "\pP" form, with the property name following the "\p", otherwise,
       braces are required.  When using braces, there is a single form, which
       is just the property name enclosed in the braces, and a compound form
       which looks like "\p{name=value}", which means to match if the property
       "name" for the character has that particular "value".  For instance, a
       match for a number can be written as "/\pN/" or as "/\p{Number}/", or
       as "/\p{Number=True}/".  Lowercase letters are matched by the property
       Lowercase_Letter which has as short form Ll. They need the braces, so
       are written as "/\p{Ll}/" or "/\p{Lowercase_Letter}/", or
       "/\p{General_Category=Lowercase_Letter}/" (the underscores are
       optional).  "/\pLl/" is valid, but means something different.  It
       matches a two character string: a letter (Unicode property "\pL"),
       followed by a lowercase "l".

       If neither the "/a" modifier nor locale rules are in effect, the use of
       a Unicode property will force the regular expression into using Unicode
       rules.

       Note that almost all properties are immune to case-insensitive
       matching.  That is, adding a "/i" regular expression modifier does not
       change what they match.  There are two sets that are affected.  The
       first set is "Uppercase_Letter", "Lowercase_Letter", and
       "Titlecase_Letter", all of which match "Cased_Letter" under "/i"
       matching.  The second set is "Uppercase", "Lowercase", and "Titlecase",
       all of which match "Cased" under "/i" matching.  (The difference
       between these sets is that some things, such as Roman Numerals, come in
       both upper and lower case so they are "Cased", but aren't considered to
       be letters, so they aren't "Cased_Letter"s. They're actually
       "Letter_Number"s.)  This set also includes its subsets "PosixUpper" and
       "PosixLower", both of which under "/i" matching match "PosixAlpha".

       For more details on Unicode properties, see "Unicode Character
       Properties" in perlunicode; for a complete list of possible properties,
       see "Properties accessible through \p{} and \P{}" in perluniprops,
       which notes all forms that have "/i" differences.  It is also possible
       to define your own properties. This is discussed in "User-Defined
       Character Properties" in perlunicode.

       Examples

        "a"  =~  /\w/      # Match, "a" is a 'word' character.
        "7"  =~  /\w/      # Match, "7" is a 'word' character as well.
        "a"  =~  /\d/      # No match, "a" isn't a digit.

        "\x{0e0b}" =~ /\p{Thai}/  # Match, \x{0e0b} is the character
                                  # 'THAI CHARACTER SO SO', and that's in
                                  # Thai Unicode class.
        "a"  =~  /\P{Lao}/ # Match, as "a" is not a Laotian character.

       It is worth emphasizing that "\d", "\w", etc, match single characters,
       not complete numbers or words. To match a number (that consists of
       digits), use "\d+"; to match a word, use "\w+".  But be aware of the
       security considerations in doing so, as mentioned above.

   Bracketed Character Classes
       The third form of character class you can use in Perl regular
       expressions is the bracketed character class.  In its simplest form, it
       lists the characters that may be matched, surrounded by square
       brackets, like this: "[aeiou]".  This matches one of "a", "e", "i", "o"
       or "u".  Like the other character classes, exactly one character is
       matched.* To match a longer string consisting of characters mentioned
       in the character class, follow the character class with a quantifier.
       For instance, "[aeiou]+" matches one or more lowercase English vowels.

       Repeating a character in a character class has no effect; it's
       considered to be in the set only once.

       Examples:

        "e"  =~  /[aeiou]/        # Match, as "e" is listed in the class.
        "p"  =~  /[aeiou]/        # No match, "p" is not listed in the class.
        "ae" =~  /^[aeiou]$/      # No match, a character class only matches
                                  # a single character.
        "ae" =~  /^[aeiou]+$/     # Match, due to the quantifier.

        -------

       * There is an exception to a bracketed character class matching only a
       single character.  When the class is to match caselessely under "/i"
       matching rules, and a character inside the class matches a multiple-
       character sequence caselessly under Unicode rules, the class (when not
       inverted) will also match that sequence.  For example, Unicode says
       that the letter "LATIN SMALL LETTER SHARP S" should match the sequence
       "ss" under "/i" rules.  Thus,

        'ss' =~ /\A\N{LATIN SMALL LETTER SHARP S}\z/i             # Matches
        'ss' =~ /\A[aeioust\N{LATIN SMALL LETTER SHARP S}]\z/i    # Matches

       Special Characters Inside a Bracketed Character Class

       Most characters that are meta characters in regular expressions (that
       is, characters that carry a special meaning like ".", "*", or "(") lose
       their special meaning and can be used inside a character class without
       the need to escape them. For instance, "[()]" matches either an opening
       parenthesis, or a closing parenthesis, and the parens inside the
       character class don't group or capture.

       char}", "\r", "\t", and "\x" are also special and have the same
       meanings as they do outside a bracketed character class.  (However,
       inside a bracketed character class, if "\N{NAME}" expands to a sequence
       of characters, only the first one in the sequence is used, with a
       warning.)

       Also, a backslash followed by two or three octal digits is considered
       an octal number.

       A "[" is not special inside a character class, unless it's the start of
       a POSIX character class (see "POSIX Character Classes" below). It
       normally does not need escaping.

       A "]" is normally either the end of a POSIX character class (see "POSIX
       Character Classes" below), or it signals the end of the bracketed
       character class.  If you want to include a "]" in the set of
       characters, you must generally escape it.

       However, if the "]" is the first (or the second if the first character
       is a caret) character of a bracketed character class, it does not
       denote the end of the class (as you cannot have an empty class) and is
       considered part of the set of characters that can be matched without
       escaping.

       Examples:

        "+"   =~ /[+?*]/     #  Match, "+" in a character class is not special.
        "\cH" =~ /[\b]/      #  Match, \b inside in a character class
                             #  is equivalent to a backspace.
        "]"   =~ /[][]/      #  Match, as the character class contains.
                             #  both [ and ].
        "[]"  =~ /[[]]/      #  Match, the pattern contains a character class
                             #  containing just ], and the character class is
                             #  followed by a ].

       Character Ranges

       It is not uncommon to want to match a range of characters. Luckily,
       instead of listing all characters in the range, one may use the hyphen
       ("-").  If inside a bracketed character class you have two characters
       separated by a hyphen, it's treated as if all characters between the
       two were in the class. For instance, "[0-9]" matches any ASCII digit,
       and "[a-m]" matches any lowercase letter from the first half of the old
       ASCII alphabet.

       Note that the two characters on either side of the hyphen are not
       necessarily both letters or both digits. Any character is possible,
       although not advisable.  "['-?]" contains a range of characters, but
       most people will not know which characters that means.  Furthermore,
       such ranges may lead to portability problems if the code has to run on
       a platform that uses a different character set, such as EBCDIC.

       If a hyphen in a character class cannot syntactically be part of a
       range, for instance because it is the first or the last character of
        [-z]        #  Matches either a hyphen ('-') or the letter 'z'.
        [a-f-m]     #  Matches any letter between 'a' and 'f' (inclusive), the
                    #  hyphen ('-'), or the letter 'm'.
        ['-?]       #  Matches any of the characters  '()*+,-./0123456789:;<=>?
                    #  (But not on an EBCDIC platform).

       Negation

       It is also possible to instead list the characters you do not want to
       match. You can do so by using a caret ("^") as the first character in
       the character class. For instance, "[^a-z]" matches any character that
       is not a lowercase ASCII letter, which therefore includes almost a
       hundred thousand Unicode letters.  The class is said to be "negated" or
       "inverted".

       This syntax make the caret a special character inside a bracketed
       character class, but only if it is the first character of the class. So
       if you want the caret as one of the characters to match, either escape
       the caret or else not list it first.

       In inverted bracketed character classes, Perl ignores the Unicode rules
       that normally say that a given character matches a sequence of multiple
       characters under caseless "/i" matching, which otherwise could be
       highly confusing:

        "ss" =~ /^[^\xDF]+$/ui;

       This should match any sequences of characters that aren't "\xDF" nor
       what "\xDF" matches under "/i".  "s" isn't "\xDF", but Unicode says
       that "ss" is what "\xDF" matches under "/i".  So which one "wins"? Do
       you fail the match because the string has "ss" or accept it because it
       has an "s" followed by another "s"?

       Examples:

        "e"  =~  /[^aeiou]/   #  No match, the 'e' is listed.
        "x"  =~  /[^aeiou]/   #  Match, as 'x' isn't a lowercase vowel.
        "^"  =~  /[^^]/       #  No match, matches anything that isn't a caret.
        "^"  =~  /[x^]/       #  Match, caret is not special here.

       Backslash Sequences

       You can put any backslash sequence character class (with the exception
       of "\N" and "\R") inside a bracketed character class, and it will act
       just as if you had put all characters matched by the backslash sequence
       inside the character class. For instance, "[a-f\d]" matches any decimal
       digit, or any of the lowercase letters between 'a' and 'f' inclusive.

       "\N" within a bracketed character class must be of the forms "\N{name}"
       or "\N{U+hex char}", and NOT be the form that matches non-newlines, for
       the same reason that a dot "." inside a bracketed character class loses
       its special meaning: it matches nearly anything, which generally isn't
       what you want to happen.

       POSIX Character Classes

       POSIX character classes have the form "[:class:]", where class is name,
       and the "[:" and ":]" delimiters. POSIX character classes only appear
       inside bracketed character classes, and are a convenient and
       descriptive way of listing a group of characters.

       Be careful about the syntax,

        # Correct:
        $string =~ /[[:alpha:]]/

        # Incorrect (will warn):
        $string =~ /[:alpha:]/

       The latter pattern would be a character class consisting of a colon,
       and the letters "a", "l", "p" and "h".  POSIX character classes can be
       part of a larger bracketed character class.  For example,

        [01[:alpha:]%]

       is valid and matches '0', '1', any alphabetic character, and the
       percent sign.

       Perl recognizes the following POSIX character classes:

        alpha  Any alphabetical character ("[A-Za-z]").
        alnum  Any alphanumeric character. ("[A-Za-z0-9]")
        ascii  Any character in the ASCII character set.
        blank  A GNU extension, equal to a space or a horizontal tab ("\t").
        cntrl  Any control character.  See Note [2] below.
        digit  Any decimal digit ("[0-9]"), equivalent to "\d".
        graph  Any printable character, excluding a space.  See Note [3] below.
        lower  Any lowercase character ("[a-z]").
        print  Any printable character, including a space.  See Note [4] below.
        punct  Any graphical character excluding "word" characters.  Note [5].
        space  Any whitespace character. "\s" plus the vertical tab ("\cK").
        upper  Any uppercase character ("[A-Z]").
        word   A Perl extension ("[A-Za-z0-9_]"), equivalent to "\w".
        xdigit Any hexadecimal digit ("[0-9a-fA-F]").

       Most POSIX character classes have two Unicode-style "\p" property
       counterparts.  (They are not official Unicode properties, but Perl
       extensions derived from official Unicode properties.)  The table below
       shows the relation between POSIX character classes and these
       counterparts.

       One counterpart, in the column labelled "ASCII-range Unicode" in the
       table, matches only characters in the ASCII character set.

       The other counterpart, in the column labelled "Full-range Unicode",
       matches any appropriate characters in the full Unicode character set.
       For example, "\p{Alpha}" matches not just the ASCII alphabetic
       characters, but any character in the entire Unicode character set
       rules is unwise unless the locale is guaranteed to be Latin-1 or UTF-8.
       In contrast, the POSIX character classes are useful under locale rules.
       They are affected by the actual rules in effect, as follows:

       If the "/a" modifier, is in effect ...
           Each of the POSIX classes matches exactly the same as their ASCII-
           range counterparts.

       otherwise ...
           For code points above 255 ...
               The POSIX class matches the same as its Full-range counterpart.

           For code points below 256 ...
               if locale rules are in effect ...
                   The POSIX class matches according to the locale.

               if Unicode rules are in effect or if on an EBCDIC platform ...
                   The POSIX class matches the same as the Full-range
                   counterpart.

               otherwise ...
                   The POSIX class matches the same as the ASCII range
                   counterpart.

       Which rules apply are determined as described in "Which character set
       modifier is in effect?" in perlre.

       It is proposed to change this behavior in a future release of Perl so
       that whether or not Unicode rules are in effect would not change the
       behavior:  Outside of locale or an EBCDIC code page, the POSIX classes
       would behave like their ASCII-range counterparts.  If you wish to
       comment on this proposal, send email to "perl5-porters@perl.org".

        [[:...:]]      ASCII-range          Full-range  backslash  Note
                        Unicode              Unicode     sequence
        -----------------------------------------------------
          alpha      \p{PosixAlpha}       \p{XPosixAlpha}
          alnum      \p{PosixAlnum}       \p{XPosixAlnum}
          ascii      \p{ASCII}
          blank      \p{PosixBlank}       \p{XPosixBlank}  \h      [1]
                                          or \p{HorizSpace}        [1]
          cntrl      \p{PosixCntrl}       \p{XPosixCntrl}          [2]
          digit      \p{PosixDigit}       \p{XPosixDigit}  \d
          graph      \p{PosixGraph}       \p{XPosixGraph}          [3]
          lower      \p{PosixLower}       \p{XPosixLower}
          print      \p{PosixPrint}       \p{XPosixPrint}          [4]
          punct      \p{PosixPunct}       \p{XPosixPunct}          [5]
                     \p{PerlSpace}        \p{XPerlSpace}   \s      [6]
          space      \p{PosixSpace}       \p{XPosixSpace}          [6]
          upper      \p{PosixUpper}       \p{XPosixUpper}
          word       \p{PosixWord}        \p{XPosixWord}   \w
          xdigit     \p{PosixXDigit}      \p{XPosixXDigit}

       [1] "\p{Blank}" and "\p{HorizSpace}" are synonyms.
       [3] Any character that is graphical, that is, visible. This class
           consists of all alphanumeric characters and all punctuation
           characters.

       [4] All printable characters, which is the set of all graphical
           characters plus those whitespace characters which are not also
           controls.

       [5] "\p{PosixPunct}" and "[[:punct:]]" in the ASCII range match all
           non-controls, non-alphanumeric, non-space characters:
           "[-!"#$%&'()*+,./:;<=>?@[\\\]^_`{|}~]" (although if a locale is in
           effect, it could alter the behavior of "[[:punct:]]").

           The similarly named property, "\p{Punct}", matches a somewhat
           different set in the ASCII range, namely
           "[-!"#%&'()*,./:;?@[\\\]_{}]".  That is, it is missing
           "[$+<=>^`|~]".  This is because Unicode splits what POSIX considers
           to be punctuation into two categories, Punctuation and Symbols.

           "\p{XPosixPunct}" and (in Unicode mode) "[[:punct:]]", match what
           "\p{PosixPunct}" matches in the ASCII range, plus what "\p{Punct}"
           matches.  This is different than strictly matching according to
           "\p{Punct}".  Another way to say it is that if Unicode rules are in
           effect, "[[:punct:]]" matches all characters that Unicode considers
           punctuation, plus all ASCII-range characters that Unicode considers
           symbols.

       [6] "\p{SpacePerl}" and "\p{Space}" differ only in that in non-locale
           matching, "\p{Space}" additionally matches the vertical tab, "\cK".
           Same for the two ASCII-only range forms.

       There are various other synonyms that can be used for these besides
       "\p{HorizSpace}" and \"\p{XPosixBlank}".  For example, "\p{PosixAlpha}"
       can be written as "\p{Alpha}".  All are listed in "Properties
       accessible through \p{} and \P{}" in perluniprops.

       Negation of POSIX character classes

       A Perl extension to the POSIX character class is the ability to negate
       it. This is done by prefixing the class name with a caret ("^").  Some
       examples:

            POSIX         ASCII-range     Full-range  backslash
                           Unicode         Unicode    sequence
        -----------------------------------------------------
        [[:^digit:]]   \P{PosixDigit}  \P{XPosixDigit}   \D
        [[:^space:]]   \P{PosixSpace}  \P{XPosixSpace}
                       \P{PerlSpace}   \P{XPerlSpace}    \S
        [[:^word:]]    \P{PerlWord}    \P{XPosixWord}    \W

       The backslash sequence can mean either ASCII- or Full-range Unicode,
       depending on various factors as described in "Which character set
       modifier is in effect?" in perlre.

                                 # except the letters 'a' to 'f'.  This is
                                 # because the main character class is composed
                                 # of two POSIX character classes that are ORed
                                 # together, one that matches any digit, and
                                 # the other that matches anything that isn't a
                                 # hex digit.  The result matches all
                                 # characters except the letters 'a' to 'f' and
                                 # 'A' to 'F'.



perl v5.14.2                      2011-09-26                PERLRECHARCLASS(1)
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