Returns the character represented by that NUMBER in the character set.
For example, C<chr(65)> is C<"A"> in either ASCII or Unicode, and
-chr(0x263a) is a Unicode smiley face. Within the scope of C<use utf8>,
-characters higher than 127 are encoded in Unicode; if you don't want
-this, temporarily C<use bytes> or use C<pack("C*",...)>
+chr(0x263a) is a Unicode smiley face. Note that characters from
+127 to 255 (inclusive) are not encoded in Unicode for backward
+compatibility reasons.
For the reverse, use L</ord>.
See L<utf8> for more about Unicode.
=item lc
Returns an 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<utf8>.
+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>.
If EXPR is omitted, uses C<$_>.
=item lcfirst
-Returns the value of EXPR with the first character lowercased. This is
-the internal function implementing the C<\l> escape in double-quoted strings.
-Respects current LC_CTYPE locale if C<use locale> in force. See L<perllocale>.
+Returns the value of EXPR with the first character lowercased. This
+is the internal function implementing the C<\l> escape in
+double-quoted strings. Respects current LC_CTYPE locale if C<use
+locale> in force. See L<perllocale> and L<perlunicode>.
If EXPR is omitted, uses C<$_>.
print STDOUT "stdout 2\n";
print STDERR "stderr 2\n";
-If you specify C<< '<&=N' >>, where C<N> is a number, then Perl will do an
-equivalent of C's C<fdopen> of that file descriptor; this is more
-parsimonious of file descriptors. For example:
+If you specify C<< '<&=N' >>, where C<N> is a number, then Perl will
+do an equivalent of C's C<fdopen> of that file descriptor; this is
+more parsimonious of file descriptors. For example:
open(FILEHANDLE, "<&=$fd")
+
or
+
open(FILEHANDLE, "<&=", $fd)
-Note that if perl is using the standard C libraries fdopen() then on many UNIX systems,
-fdopen() is known to fail when file descriptors
+Note that if Perl is using the standard C libraries' fdopen() then on
+many UNIX systems, fdopen() is known to fail when file descriptors
exceed a certain value, typically 255. If you need more file
descriptors than that, consider rebuilding Perl to use the C<PerlIO>.
+You can see whether Perl has been compiled with PerlIO or not by
+running C<perl -V> and looking for C<useperlio=> line. If C<useperlio>
+is C<define>, you have PerlIO, otherwise you don't.
+
If you open a pipe on the command C<'-'>, i.e., either C<'|-'> or C<'-|'>
with 2-arguments (or 1-argument) form of open(), then
there is an implicit fork done, and the return value of open is the pid
changed or removed in future releases of Perl. It should not be
relied upon.
-The only currently recognized attribute is C<shared> which indicates
+The only currently recognized attribute is C<unique> which indicates
that a single copy of the global is to be used by all interpreters
should the program happen to be running in a multi-interpreter
environment. (The default behaviour would be for each interpreter to
attribute also has the effect of making the global readonly.
Examples:
- our @EXPORT : shared = qw(foo);
- our %EXPORT_TAGS : shared = (bar => [qw(aa bb cc)]);
- our $VERSION : shared = "1.00";
+ our @EXPORT : unique = qw(foo);
+ our %EXPORT_TAGS : unique = (bar => [qw(aa bb cc)]);
+ our $VERSION : unique = "1.00";
Multi-interpreter environments can come to being either through the
fork() emulation on Windows platforms, or by embedding perl in a
-multi-threaded application. The C<shared> attribute does nothing in
+multi-threaded application. The C<unique> attribute does nothing in
all other environments.
=item pack TEMPLATE,LIST
P A pointer to a structure (fixed-length string).
u A uuencoded string.
- U A Unicode character number. Encodes to UTF-8 internally.
- Works even if C<use utf8> is not in effect.
+ U A Unicode character number. Encodes to UTF-8 internally
+ (or UTF-EBCDIC in EBCDIC platforms).
w A BER compressed integer. Its bytes represent an unsigned
integer in base 128, most significant digit first, with as
still seen in older code).
If NAMESPACE is omitted, then there is no current package, and all
-identifiers must be fully qualified or lexicals. This is stricter
-than C<use strict>, since it also extends to function names.
+identifiers must be fully qualified or lexicals. However, you are
+strongly advised not to make use of this feature. Its use can cause
+unexpected behaviour, even crashing some versions of Perl. It is
+deprecated, and will be removed from a future release.
See L<perlmod/"Packages"> for more information about packages, modules,
and classes. See L<perlsub> for other scoping issues.
Equivalent to C<print FILEHANDLE sprintf(FORMAT, LIST)>, except that C<$\>
(the output record separator) is not appended. The first argument
-of the list will be interpreted as the C<printf> format. If C<use locale> is
-in effect, the character used for the decimal point in formatted real numbers
-is affected by the LC_NUMERIC locale. See L<perllocale>.
+of the list will be interpreted as the C<printf> format. See C<sprintf>
+for an explanation of the format argument. If C<use locale> is in effect,
+the character used for the decimal point in formatted real numbers is
+affected by the LC_NUMERIC locale. See L<perllocale>.
Don't fall into the trap of using a C<printf> when a simple
C<print> would do. The C<print> is more efficient and less
=item semop KEY,OPSTRING
Calls the System V IPC function semop to perform semaphore operations
-such as signaling and waiting. OPSTRING must be a packed array of
+such as signalling and waiting. OPSTRING must be a packed array of
semop structures. Each semop structure can be generated with
-C<pack("sss", $semnum, $semop, $semflag)>. The number of semaphore
+C<pack("s!3", $semnum, $semop, $semflag)>. The number of semaphore
operations is implied by the length of OPSTRING. Returns true if
successful, or false if there is an error. As an example, the
following code waits on semaphore $semnum of semaphore id $semid:
- $semop = pack("sss", $semnum, -1, 0);
+ $semop = pack("s!3", $semnum, -1, 0);
die "Semaphore trouble: $!\n" unless semop($semid, $semop);
To signal the semaphore, replace C<-1> with C<1>. See also
produces the output 'h:i:t:h:e:r:e'.
+Using the empty pattern C<//> specifically matches the null string, and is
+not be confused with the use of C<//> to mean "the last successful pattern
+match".
+
Empty leading (or trailing) fields are produced when there positive width
matches at the beginning (or end) of the string; a zero-width match at the
beginning (or end) of the string does not produce an empty field. For
#...
}
+As with regular pattern matching, any capturing parentheses that are not
+matched in a C<split()> will be set to C<undef> when returned:
+
+ @fields = split /(A)|B/, "1A2B3";
+ # @fields is (1, 'A', 2, undef, 3)
=item sprintf FORMAT, LIST
($user,$system,$cuser,$csystem) = times;
+In scalar context, C<times> returns C<$user>.
+
=item tr///
The transliteration operator. Same as C<y///>. See L<perlop>.
=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>.
-Under Unicode (C<use utf8>) it uses the standard Unicode uppercase mappings. (It
-does not attempt to do titlecase mapping on initial letters. See C<ucfirst> for that.)
+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>. Under Unicode it uses the standard Unicode
+uppercase mappings. (It does not attempt to do titlecase mapping on
+initial letters. See C<ucfirst> for that.)
If EXPR is omitted, uses C<$_>.
=item ucfirst
-Returns the value of EXPR with the first character
-in uppercase (titlecase in Unicode). This is
-the internal function implementing the C<\u> escape in double-quoted strings.
-Respects current LC_CTYPE locale if C<use locale> in force. See L<perllocale>
-and L<utf8>.
+Returns the value of EXPR with the first character in uppercase
+(titlecase in Unicode). This is the internal function implementing
+the C<\u> escape in double-quoted strings. Respects current LC_CTYPE
+locale if C<use locale> in force. See L<perllocale> and L<perlunicode>.
If EXPR is omitted, uses C<$_>.
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