=head2 OPERATORS
- =~ determines to which variable the regex is applied.
- In its absence, $_ is used.
+C<=~> determines to which variable the regex is applied.
+In its absence, $_ is used.
- $var =~ /foo/;
+ $var =~ /foo/;
- !~ determines to which variable the regex is applied,
- and negates the result of the match; it returns
- false if the match succeeds, and true if it fails.
+C<!~> determines to which variable the regex is applied,
+and negates the result of the match; it returns
+false if the match succeeds, and true if it fails.
- $var !~ /foo/;
+ $var !~ /foo/;
- m/pattern/igmsoxc searches a string for a pattern match,
- applying the given options.
+C<m/pattern/msixpogc> searches a string for a pattern match,
+applying the given options.
- i case-Insensitive
- g Global - all occurrences
- m Multiline mode - ^ and $ match internal lines
- s match as a Single line - . matches \n
- o compile pattern Once
- x eXtended legibility - free whitespace and comments
- c don't reset pos on failed matches when using /g
+ m Multiline mode - ^ and $ match internal lines
+ s match as a Single line - . matches \n
+ i case-Insensitive
+ x eXtended legibility - free whitespace and comments
+ p Preserve a copy of the matched string -
+ ${^PREMATCH}, ${^MATCH}, ${^POSTMATCH} will be defined.
+ o compile pattern Once
+ g Global - all occurrences
+ c don't reset pos on failed matches when using /g
- If 'pattern' is an empty string, the last I<successfully> matched
- regex is used. Delimiters other than '/' may be used for both this
- operator and the following ones.
+If 'pattern' is an empty string, the last I<successfully> matched
+regex is used. Delimiters other than '/' may be used for both this
+operator and the following ones. The leading C<m> can be ommitted
+if the delimiter is '/'.
- qr/pattern/imsox lets you store a regex in a variable,
- or pass one around. Modifiers as for m// and are stored
- within the regex.
+C<qr/pattern/msixpo> lets you store a regex in a variable,
+or pass one around. Modifiers as for C<m//>, and are stored
+within the regex.
- s/pattern/replacement/igmsoxe substitutes matches of
- 'pattern' with 'replacement'. Modifiers as for m//
- with one addition:
+C<s/pattern/replacement/msixpogce> substitutes matches of
+'pattern' with 'replacement'. Modifiers as for C<m//>,
+with one addition:
- e Evaluate replacement as an expression
+ e Evaluate 'replacement' as an expression
- 'e' may be specified multiple times. 'replacement' is interpreted
- as a double quoted string unless a single-quote (') is the delimiter.
+'e' may be specified multiple times. 'replacement' is interpreted
+as a double quoted string unless a single-quote (C<'>) is the delimiter.
- ?pattern? is like m/pattern/ but matches only once. No alternate
- delimiters can be used. Must be reset with reset().
+C<?pattern?> is like C<m/pattern/> but matches only once. No alternate
+delimiters can be used. Must be reset with reset().
=head2 SYNTAX
(...) Groups subexpressions for capturing to $1, $2...
(?:...) Groups subexpressions without capturing (cluster)
| Matches either the subexpression preceding or following it
- \1, \2 ... The text from the Nth group
+ \1, \2 ... Matches the text from the Nth group
=head2 ESCAPE SEQUENCES
\L Lowercase until \E
\U Uppercase until \E
\Q Disable pattern metacharacters until \E
- \E End case modification
+ \E End modification
For Titlecase, see L</Titlecase>.
[^f-j] Caret indicates "match any character _except_ these"
The following sequences work within or without a character class.
-The first six are locale aware, all are Unicode aware. The default
-character class equivalent are given. See L<perllocale> and
-L<perlunicode> for details.
-
- \d A digit [0-9]
- \D A nondigit [^0-9]
- \w A word character [a-zA-Z0-9_]
- \W A non-word character [^a-zA-Z0-9_]
- \s A whitespace character [ \t\n\r\f]
- \S A non-whitespace character [^ \t\n\r\f]
+The first six are locale aware, all are Unicode aware. See L<perllocale>
+and L<perlunicode> for details.
+
+ \d A digit
+ \D A nondigit
+ \w A word character
+ \W A non-word character
+ \s A whitespace character
+ \S A non-whitespace character
+ \h An horizontal white space
+ \H A non horizontal white space
+ \v A vertical white space
+ \V A non vertical white space
+ \R A generic newline (?>\v|\x0D\x0A)
\C Match a byte (with Unicode, '.' matches a character)
\pP Match P-named (Unicode) property
\p{...} Match Unicode property with long name
\PP Match non-P
\P{...} Match lack of Unicode property with long name
- \X Match extended unicode sequence
+ \X Match extended Unicode combining character sequence
POSIX character classes and their Unicode and Perl equivalents:
=head2 VARIABLES
$_ Default variable for operators to use
- $* Enable multiline matching (deprecated; not in 5.9.0 or later)
- $& Entire matched string
$` Everything prior to matched string
+ $& Entire matched string
$' Everything after to matched string
-The use of those last three will slow down B<all> regex use
+ ${^PREMATCH} Everything prior to matched string
+ ${^MATCH} Entire matched string
+ ${^POSTMATCH} Everything after to matched string
+
+The use of C<$`>, C<$&> or C<$'> will slow down B<all> regex use
within your program. Consult L<perlvar> for C<@LAST_MATCH_START>
to see equivalent expressions that won't cause slow down.
-See also L<Devel::SawAmpersand>.
+See also L<Devel::SawAmpersand>. Starting with Perl 5.10, you
+can also use the equivalent variables C<${^PREMATCH}>, C<${^MATCH}>
+and C<${^POSTMATCH}>, but for them to be defined, you have to
+specify the C</p> (preserve) modifier on your regular expression.
$1, $2 ... hold the Xth captured expr
$+ Last parenthesized pattern match
$^R Holds the result of the last (?{...}) expr
@- Offsets of starts of groups. $-[0] holds start of whole match
@+ Offsets of ends of groups. $+[0] holds end of whole match
+ %+ Named capture buffers
+ %- Named capture buffers, as array refs
Captured groups are numbered according to their I<opening> paren.
reset Reset ?pattern? status
study Analyze string for optimizing matching
- split Use regex to split a string into parts
+ split Use a regex to split a string into parts
The first four of these are like the escape sequences C<\L>, C<\l>,
C<\U>, and C<\u>. For Titlecase, see L</Titlecase>.
=item *
-L<perluniintro>, L<perlunicode>, L<charnames> and L<locale>
+L<perluniintro>, L<perlunicode>, L<charnames> and L<perllocale>
for details on regexes and internationalisation.
=item *
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