=over 8
+=item $a
+
+=item $b
+
+Special package variables when using sort(), see L<perlfunc/sort>.
+Because of this specialness $a and $b don't need to be declared
+(using local(), use vars, or our()) even when using the strict
+vars pragma. Don't lexicalize them with C<my $a> or C<my $b>
+if you want to be able to use them in the sort() comparison block
+or function.
+
+=back
+
+=over 8
+
=item $<I<digits>>
Contains the subpattern from the corresponding set of capturing
=item $+
-The last bracket matched by the last search pattern. This is useful if
-you don't know which one of a set of alternative patterns matched. For
-example:
+The text matched by the last bracket of the last successful search pattern.
+This is useful if you don't know which one of a set of alternative patterns
+matched. For example:
/Version: (.*)|Revision: (.*)/ && ($rev = $+);
(Mnemonic: be positive and forward looking.)
This variable is read-only and dynamically scoped to the current BLOCK.
+=item $^N
+
+The text matched by the used group most-recently closed (i.e. the group
+with the rightmost closing parenthesis) of the last successful search
+pattern. (Mnemonic: the (possibly) Nested parenthesis that most
+recently closed.)
+
+This is primarly used inside C<(?{...})> blocks for examining text
+recently matched. For example, to effectively capture text to a variable
+(in addition to C<$1>, C<$2>, etc.), replace C<(...)> with
+
+ (?:(...)(?{ $var = $^N }))
+
+By setting and then using C<$var> in this way relieves you from having to
+worry about exactly which numbered set of parentheses they are.
+
+This variable is dynamically scoped to the current BLOCK.
+
=item @LAST_MATCH_END
=item @+
=item $*
-Set to 1 to do multi-line matching within a string, 0 to tell Perl
-that it can assume that strings contain a single line, for the purpose
-of optimizing pattern matches. Pattern matches on strings containing
-multiple newlines can produce confusing results when C<$*> is 0. Default
-is 0. (Mnemonic: * matches multiple things.) This variable
-influences the interpretation of only C<^> and C<$>. A literal newline can
-be searched for even when C<$* == 0>.
+Set to a non-zero integer value to do multi-line matching within a
+string, 0 (or undefined) to tell Perl that it can assume that strings
+contain a single line, for the purpose of optimizing pattern matches.
+Pattern matches on strings containing multiple newlines can produce
+confusing results when C<$*> is 0 or undefined. Default is undefined.
+(Mnemonic: * matches multiple things.) This variable influences the
+interpretation of only C<^> and C<$>. A literal newline can be searched
+for even when C<$* == 0>.
Use of C<$*> is deprecated in modern Perl, supplanted by
the C</s> and C</m> modifiers on pattern matching.
+Assigning a non-numerical value to C<$*> triggers a warning (and makes
+C<$*> act if C<$* == 0>), while assigning a numerical value to C<$*>
+makes that an implicit C<int> is applied on the value.
+
=item input_line_number HANDLE EXPR
=item $INPUT_LINE_NUMBER
successful submatches in the currently active dynamic scope.
C<$-[0]> is the offset into the string of the beginning of the
entire match. The I<n>th element of this array holds the offset
-of the I<n>th submatch, so C<$+[1]> is the offset where $1
-begins, C<$+[2]> the offset where $2 begins, and so on.
-You can use C<$#-> to determine how many subgroups were in the
-last successful match. Compare with the C<@+> variable.
+of the I<n>th submatch, so C<$-[1]> is the offset where $1
+begins, C<$-[2]> the offset where $2 begins, and so on.
After a match against some variable $var:
Under VMS, the pragma C<use vmsish 'status'> makes C<$?> reflect the
actual VMS exit status, instead of the default emulation of POSIX
-status.
+status; see L<perlvms/$?> for details.
Also see L<Error Indicators>.
=item $@
-The Perl syntax error message from the last eval() operator. If null, the
-last eval() parsed and executed correctly (although the operations you
-invoked may have failed in the normal fashion). (Mnemonic: Where was
-the syntax error "at"?)
+The Perl syntax error message from the last eval() operator.
+If $@ is the null string, the last eval() parsed and executed
+correctly (although the operations you invoked may have failed in the
+normal fashion). (Mnemonic: Where was the syntax error "at"?)
Warning messages are not collected in this variable. You can,
however, set up a routine to process warnings by setting C<$SIG{__WARN__}>
script is in the right range of versions. (Mnemonic: use ^V for Version
Control.) Example:
- warn "No "our" declarations!\n" if $^V and $^V lt v5.6.0;
+ warn "No \"our\" declarations!\n" if $^V and $^V lt v5.6.0;
See the documentation of C<use VERSION> and C<require VERSION>
for a convenient way to fail if the running Perl interpreter is too old.
one, because C<$ARGV[0]> is the first argument, I<not> the program's
command name itself. See C<$0> for the command name.
+=item @F
+
+The array @F contains the fields of each line read in when autosplit
+mode is turned on. See L<perlrun> for the B<-a> switch. This array
+is package-specific, and must be declared or given a full package name
+if not in package main when running under C<strict 'vars'>.
+
=item @INC
The array @INC contains the list of places that the C<do EXPR>,
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