=item lc
Returns a lowercased version of EXPR. This is the internal function
-implementing the C<\L> escape in double-quoted strings. Respects
-current LC_CTYPE locale if C<use locale> in force. See L<perllocale>
-and L<perlunicode> for more details about locale and Unicode support.
+implementing the C<\L> escape in double-quoted strings.
If EXPR is omitted, uses C<$_>.
+What gets returned depends on several factors:
+
+=over
+
+=item If C<use bytes> is in effect:
+
+=over
+
+=item On EBCDIC platforms
+
+The results are what the C language system call C<tolower()> returns.
+
+=item On ASCII platforms
+
+The results follow ASCII semantics. Only characters C<A-Z> change, to C<a-z>
+respectively.
+
+=back
+
+=item Otherwise, If EXPR has the UTF8 flag set
+
+If the current package has a subroutine named C<ToLower>, it will be used to
+change the case (See L<perlunicode/User-Defined Case Mappings>.)
+Otherwise Unicode semantics are used for the case change.
+
+=item Otherwise, if C<use locale> is in effect
+
+Respects current LC_CTYPE locale. See L<perllocale>.
+
+=item Otherwise, if C<use feature 'unicode_strings'> is in effect:
+
+Unicode semantics are used for the case change. Any subroutine named
+C<ToLower> will not be used.
+
+=item Otherwise:
+
+=over
+
+=item On EBCDIC platforms
+
+The results are what the C language system call C<tolower()> returns.
+
+=item On ASCII platforms
+
+ASCII semantics are used for the case change. The lowercase of any character
+outside the ASCII range is the character itself.
+
+=back
+
+=back
+
=item lcfirst EXPR
X<lcfirst> X<lowercase>
Returns the value of EXPR with the first character lowercased. This
is the internal function implementing the C<\l> escape in
-double-quoted strings. Respects current LC_CTYPE locale if C<use
-locale> in force. See L<perllocale> and L<perlunicode> for more
-details about locale and Unicode support.
+double-quoted strings.
If EXPR is omitted, uses C<$_>.
+This function behaves the same way under various pragma, such as in a locale,
+as L</lc> does.
+
=item length EXPR
X<length> X<size>
an integer may be represented by a sequence of 4 bytes that will be
converted to a sequence of 4 characters.
+See L<perlpacktut> for an introduction to this function.
+
The TEMPLATE is a sequence of characters that give the order and type
of values, as follows:
If EXPR is omitted, uses C<$_>.
+quotemeta (and C<\Q> ... C<\E>) are useful when interpolating strings into
+regular expressions, because by default an interpolated variable will be
+considered a mini-regular expression. For example:
+
+ my $sentence = 'The quick brown fox jumped over the lazy dog';
+ my $substring = 'quick.*?fox';
+ $sentence =~ s{$substring}{big bad wolf};
+
+Will cause C<$sentence> to become C<'The big bad wolf jumped over...'>.
+
+On the other hand:
+
+ my $sentence = 'The quick brown fox jumped over the lazy dog';
+ my $substring = 'quick.*?fox';
+ $sentence =~ s{\Q$substring\E}{big bad wolf};
+
+Or:
+
+ my $sentence = 'The quick brown fox jumped over the lazy dog';
+ my $substring = 'quick.*?fox';
+ my $quoted_substring = quotemeta($substring);
+ $sentence =~ s{$quoted_substring}{big bad wolf};
+
+Will both leave the sentence as is. Normally, when accepting string input from
+the user, quotemeta() or C<\Q> must be used.
+
=item rand EXPR
X<rand> X<random>
=item uc
Returns an uppercased version of EXPR. This is the internal function
-implementing the C<\U> escape in double-quoted strings. Respects
-current LC_CTYPE locale if C<use locale> in force. See L<perllocale>
-and L<perlunicode> for more details about locale and Unicode support.
+implementing the C<\U> escape in double-quoted strings.
It does not attempt to do titlecase mapping on initial letters. See
C<ucfirst> for that.
If EXPR is omitted, uses C<$_>.
+This function behaves the same way under various pragma, such as in a locale,
+as L</lc> does.
+
=item ucfirst EXPR
X<ucfirst> X<uppercase>
Returns the value of EXPR with the first character in uppercase
(titlecase in Unicode). This is the internal function implementing
-the C<\u> escape in double-quoted strings. Respects current LC_CTYPE
-locale if C<use locale> in force. See L<perllocale> and L<perlunicode>
-for more details about locale and Unicode support.
+the C<\u> escape in double-quoted strings.
If EXPR is omitted, uses C<$_>.
+This function behaves the same way under various pragma, such as in a locale,
+as L</lc> does.
+
=item umask EXPR
X<umask>
and expands it out into a list of values.
(In scalar context, it returns merely the first value produced.)
-If EXPR is omitted, unpacks the C<$_> string.
+If EXPR is omitted, unpacks the C<$_> string. for an introduction to this function.
+
+See L<perlpacktut> for an introduction to this function.
The string is broken into chunks described by the TEMPLATE. Each chunk
is converted separately to a value. Typically, either the string is a result
which import symbols into the current package (which are effective
through the end of the file).
+Because C<use> takes effect at compile time, it doesn't respect the
+ordinary flow control of the code being compiled. In particular, putting
+a C<use> inside the false branch of a conditional doesn't prevent it
+from being processed. If a module or pragma needs to be loaded only
+conditionally, this can be done using the L<if> pragma:
+
+ use if $] < 5.008, "utf8";
+ use if WANT_WARNINGS, warnings => qw(all);
+
There's a corresponding C<no> command that unimports meanings imported
by C<use>, i.e., it calls C<unimport Module LIST> instead of C<import>.
It behaves exactly as C<import> does with respect to VERSION, an
projects / p5sagit/p5-mst-13.2.git / blobdiff