=item Functions for SCALARs or strings
C<chomp>, C<chop>, C<chr>, C<crypt>, C<hex>, C<index>, C<lc>, C<lcfirst>,
-C<length>, C<oct>, C<ord>, C<pack>, C<q>/STRING/, C<qq>/STRING/, C<reverse>,
-C<rindex>, C<sprintf>, C<substr>, C<tr///>, C<uc>, C<ucfirst>, C<y>///
+C<length>, C<oct>, C<ord>, C<pack>, C<q/STRING/>, C<qq/STRING/>, C<reverse>,
+C<rindex>, C<sprintf>, C<substr>, C<tr///>, C<uc>, C<ucfirst>, C<y///>
=item Regular expressions and pattern matching
-C<m>//, C<pos>, C<quotemeta>, C<s>///, C<split>, C<study>, C<qr//>
+C<m//>, C<pos>, C<quotemeta>, C<s///>, C<split>, C<study>, C<qr//>
=item Numeric functions
=item Functions for list data
-C<grep>, C<join>, C<map>, C<qw>/STRING/, C<reverse>, C<sort>, C<unpack>
+C<grep>, C<join>, C<map>, C<qw/STRING/>, C<reverse>, C<sort>, C<unpack>
=item Functions for real %HASHes
=item Functions for processes and process groups
C<alarm>, C<exec>, C<fork>, C<getpgrp>, C<getppid>, C<getpriority>, C<kill>,
-C<pipe>, C<qx>/STRING/, C<setpgrp>, C<setpriority>, C<sleep>, C<system>,
+C<pipe>, C<qx/STRING/>, C<setpgrp>, C<setpriority>, C<sleep>, C<system>,
C<times>, C<wait>, C<waitpid>
=item Keywords related to perl modules
and C<sleep()> calls.
If you want to use C<alarm()> to time out a system call you need to use an
-C<eval>/C<die> pair. You can't rely on the alarm causing the system call to
+C<eval()>/C<die()> pair. You can't rely on the alarm causing the system call to
fail with C<$!> set to EINTR because Perl sets up signal handlers to
-restart system calls on some systems. Using C<eval>/C<die> always works,
+restart system calls on some systems. Using C<eval()>/C<die()> always works,
modulo the caveats given in L<perlipc/"Signals">.
eval {
translated to CR LF on output. Binmode has no effect under Unix; in MS-DOS
and similarly archaic systems, it may be imperative--otherwise your
MS-DOS-damaged C library may mangle your file. The key distinction between
-systems that need C<binmode> and those that don't is their text file
+systems that need C<binmode()> and those that don't is their text file
formats. Systems like Unix, MacOS, and Plan9 that delimit lines with a single
character, and that encode that character in C as C<"\n">, do not need
-C<binmode>. The rest need it. If FILEHANDLE is an expression, the value
+C<binmode()>. The rest need it. If FILEHANDLE is an expression, the value
is taken as the name of the filehandle.
=item bless REF,CLASSNAME
$hasargs, $wantarray, $evaltext, $is_require) = caller($i);
Here C<$subroutine> may be C<"(eval)"> if the frame is not a subroutine
-call, but an C<eval>. In such a case additional elements C<$evaltext> and
+call, but an C<eval()>. In such a case additional elements C<$evaltext> and
C<$is_require> are set: C<$is_require> is true if the frame is created by a
C<require> or C<use> statement, C<$evaltext> contains the text of the
C<eval EXPR> statement. In particular, for a C<eval BLOCK> statement,
arguments with which the subroutine was invoked.
Be aware that the optimizer might have optimized call frames away before
-C<caller> had a chance to get the information. That means that C<caller(N)>
+C<caller()> had a chance to get the information. That means that C<caller(N)>
might not return information about the call frame you expect it do, for
C<N E<gt> 1>. In particular, C<@DB::args> might have information from the
previous time C<caller()> was called.
chop($answer = <STDIN>);
If you chop a list, each element is chopped. Only the value of the
-last C<chop> is returned.
+last C<chop()> is returned.
-Note that C<chop> returns the last character. To return all but the last
+Note that C<chop()> returns the last character. To return all but the last
character, use C<substr($string, 0, -1)>.
=item chown LIST
begin with a C<"/"> by your process and all its children. (It doesn't
change your current working directory, which is unaffected.) For security
reasons, this call is restricted to the superuser. If FILENAME is
-omitted, does a C<chroot> to C<$_>.
+omitted, does a C<chroot()> to C<$_>.
=item close FILEHANDLE
You don't have to close FILEHANDLE if you are immediately going to do
another C<open()> on it, because C<open()> will close it for you. (See
-C<open()>.) However, an explicit C<close> on an input file resets the line
+C<open()>.) However, an explicit C<close()> on an input file resets the line
counter (C<$.>), while the implicit close done by C<open()> does not.
-If the file handle came from a piped open C<close> will additionally
+If the file handle came from a piped open C<close()> will additionally
return FALSE if one of the other system calls involved fails or if the
program exits with non-zero status. (If the only problem was that the
program exited non-zero C<$!> will be set to C<0>.) Also, closing a pipe
[This function has been superseded by the C<tie()> function.]
This binds a dbm(3), ndbm(3), sdbm(3), gdbm(3), or Berkeley DB file to a
-hash. HASH is the name of the hash. (Unlike normal C<open>, the first
+hash. HASH is the name of the hash. (Unlike normal C<open()>, the first
argument is I<NOT> a filehandle, even though it looks like one). DBNAME
is the name of the database (without the F<.dir> or F<.pag> extension if
any). If the database does not exist, it is created with protection
be subject to its quirks and capabilities. See L<perlop/"`STRING`">
for details.
-Using an indirect object with C<exec> or C<system> is also more secure.
+Using an indirect object with C<exec()> or C<system()> is also more secure.
This usage forces interpretation of the arguments as a multivalued list,
even if the list had just one argument. That way you're safe from the
shell expanding wildcards or splitting up words with whitespace in them.
didn't--it tried to run a program literally called I<"echo surprise">,
didn't find it, and set C<$?> to a non-zero value indicating failure.
-Note that C<exec> will not call your C<END> blocks, nor will it call
+Note that C<exec()> will not call your C<END> blocks, nor will it call
any C<DESTROY> methods in your objects.
=item exists EXPR
fcntl($filehandle, F_GETFL, $packed_return_buffer)
or die "can't fcntl F_GETFL: $!";
-You don't have to check for C<defined> on the return from
-C<fnctl>. Like C<ioctl>, it maps a C<0> return from the system
+You don't have to check for C<defined()> on the return from
+C<fnctl()>. Like C<ioctl()>, it maps a C<0> return from the system
call into "C<0> but true" in Perl. This string is true in
boolean context and C<0> in numeric context. It is also
exempt from the normal B<-w> warnings on improper numeric
or to get out of a block or subroutine given to C<sort()>.
It can be used to go almost anywhere else within the dynamic scope,
including out of subroutines, but it's usually better to use some other
-construct such as C<last> or C<die>. The author of Perl has never felt the
+construct such as C<last> or C<die()>. The author of Perl has never felt the
need to use this form of C<goto> (in Perl, that is--C is another matter).
The C<goto-EXPR> form expects a label name, whose scope will be resolved
array. Similarly, grep returns aliases into the original list,
much like the way that a for loops's index variable aliases the list
elements. That is, modifying an element of a list returned by grep
-(for example, in a C<foreach>, C<map> or another C<grep>)
+(for example, in a C<foreach>, C<map()> or another C<grep()>)
actually modifies the element in the original list.
See also L</map> for an array composed of the results of the BLOCK or EXPR.
(There is a Perl script called B<h2ph> that comes with the Perl kit that
may help you in this, but it's nontrivial.) SCALAR will be read and/or
written depending on the FUNCTION--a pointer to the string value of SCALAR
-will be passed as the third argument of the actual C<ioctl> call. (If SCALAR
+will be passed as the third argument of the actual C<ioctl()> call. (If SCALAR
has no string value but does have a numeric value, that value will be
passed rather than a pointer to the string value. To guarantee this to be
TRUE, add a C<0> to the scalar before using it.) The C<pack()> and C<unpack()>
|| die "Can't ioctl: $!";
}
-The return value of C<ioctl> (and C<fcntl>) is as follows:
+The return value of C<ioctl()> (and C<fcntl()>) is as follows:
if OS returns: then Perl returns:
-1 undefined value
print $key, '=', $ENV{$key}, "\n";
}
-To sort an array by value, you'll need to use a C<sort> function.
+To sort an array by value, you'll need to use a C<sort()> function.
Here's a descending numeric sort of a hash by its values:
foreach $key (sort { $hash{$b} <=> $hash{$a} } keys %hash) {
printf "%4d %s\n", $hash{$key}, $key;
}
-As an lvalue C<keys> allows you to increase the number of hash buckets
+As an lvalue C<keys()> allows you to increase the number of hash buckets
allocated for the given hash. This can gain you a measure of efficiency if
you know the hash is going to get big. (This is similar to pre-extending
an array by assigning a larger number to $#array.) If you say
buckets will be retained even if you do C<%hash = ()>, use C<undef
%hash> if you want to free the storage while C<%hash> is still in scope.
You can't shrink the number of buckets allocated for the hash using
-C<keys> in this way (but you needn't worry about doing this by accident,
+C<keys()> in this way (but you needn't worry about doing this by accident,
as trying has no effect).
=item kill LIST
first to get the correct constant definitions. If CMD is C<IPC_STAT>,
then ARG must be a variable which will hold the returned C<msqid_ds>
-structure. Returns like C<ioctl>: the undefined value for error, "C<0> but
+structure. Returns like C<ioctl()>: the undefined value for error, "C<0> but
true" for zero, or the actual return value otherwise. See also
C<IPC::SysV> and C<IPC::Semaphore::Msg> documentation.
=item my EXPR
-A C<my> declares the listed variables to be local (lexically) to the
-enclosing block, file, or C<eval>. If
+A C<my()> declares the listed variables to be local (lexically) to the
+enclosing block, file, or C<eval()>. If
more than one value is listed, the list must be placed in parentheses. See
L<perlsub/"Private Variables via my()"> for details.
FILEHANDLE. If FILEHANDLE is an expression, its value is used as the
name of the real filehandle wanted. If EXPR is omitted, the scalar
variable of the same name as the FILEHANDLE contains the filename.
-(Note that lexical variables--those declared with C<my>--will not work
-for this purpose; so if you're using C<my>, specify EXPR in your call
+(Note that lexical variables--those declared with C<my()>--will not work
+for this purpose; so if you're using C<my()>, specify EXPR in your call
to open.)
If the filename begins with C<'E<lt>'> or nothing, the file is opened for input.
and L<perlipc/"Bidirectional Communication"> for alternatives.)
Opening C<'-'> opens STDIN and opening C<'E<gt>-'> opens STDOUT. Open returns
-nonzero upon success, the undefined value otherwise. If the C<open>
+nonzero upon success, the undefined value otherwise. If the C<open()>
involved a pipe, the return value happens to be the pid of the
subprocess.
If you're unfortunate enough to be running Perl on a system that
distinguishes between text files and binary files (modern operating
systems don't care), then you should check out L</binmode> for tips for
-dealing with this. The key distinction between systems that need C<binmode>
+dealing with this. The key distinction between systems that need C<binmode()>
and those that don't is their text file formats. Systems like Unix, MacOS, and
Plan9, which delimit lines with a single character, and which encode that
-character in C as C<"\n">, do not need C<binmode>. The rest need it.
+character in C as C<"\n">, do not need C<binmode()>. The rest need it.
When opening a file, it's usually a bad idea to continue normal execution
-if the request failed, so C<open> is frequently used in connection with
-C<die>. Even if C<die> won't do what you want (say, in a CGI script,
+if the request failed, so C<open()> is frequently used in connection with
+C<die()>. Even if C<die()> won't do what you want (say, in a CGI script,
where you want to make a nicely formatted error message (but there are
modules that can help with that problem)) you should always check
the return value from opening a file. The infrequent exception is when
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
+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>.
If FUNCTION is a string starting with C<CORE::>, the rest is taken as
a name for Perl builtin. If builtin is not I<overridable> (such as
-C<qw>) or its arguments cannot be expressed by a prototype (such as
-C<system>) - in other words, the builtin does not behave like a Perl
+C<qw//>) or its arguments cannot be expressed by a prototype (such as
+C<system()>) - in other words, the builtin does not behave like a Perl
function - returns C<undef>. Otherwise, the string describing the
equivalent prototype is returned.
=item seek FILEHANDLE,POSITION,WHENCE
-Sets FILEHANDLE's position, just like the C<fseek()> call of C<stdio>.
+Sets FILEHANDLE's position, just like the C<fseek()> call of C<stdio()>.
FILEHANDLE may be an expression whose value gives the name of the
filehandle. The values for WHENCE are C<0> to set the new position to
POSITION, C<1> to set it to the current position plus POSITION, and C<2> to
Returns the currently selected filehandle. Sets the current default
filehandle for output, if FILEHANDLE is supplied. This has two
-effects: first, a C<write> or a C<print> without a filehandle will
+effects: first, a C<write()> or a C<print()> without a filehandle will
default to this FILEHANDLE. Second, references to variables related to
output will refer to this output channel. For example, if you have to
set the top of form format for more than one output channel, you might
=item semctl ID,SEMNUM,CMD,ARG
-Calls the System V IPC function C<semctl>. You'll probably have to say
+Calls the System V IPC function C<semctl()>. You'll probably have to say
use IPC::SysV;
first to get the correct constant definitions. If CMD is IPC_STAT or
GETALL, then ARG must be a variable which will hold the returned
-semid_ds structure or semaphore value array. Returns like C<ioctl>: the
+semid_ds structure or semaphore value array. Returns like C<ioctl()>: the
undefined value for error, "C<0> but true" for zero, or the actual return
value otherwise. See also C<IPC::SysV> and C<IPC::Semaphore> documentation.
for the system call of the same name. If unimplemented, yields a fatal
error. Returns TRUE if successful.
-Some systems defined C<pipe()> in terms of C<socketpair>, in which a call
+Some systems defined C<pipe()> in terms of C<socketpair()>, in which a call
to C<pipe(Rdr, Wtr)> is essentially:
use Socket;
=item sort LIST
Sorts the LIST and returns the sorted list value. If SUBNAME or BLOCK
-is omitted, C<sort>s in standard string comparison order. If SUBNAME is
+is omitted, C<sort()>s in standard string comparison order. If SUBNAME is
specified, it gives the name of a subroutine that returns an integer
less than, equal to, or greater than C<0>, depending on how the elements
of the array are to be ordered. (The C<E<lt>=E<gt>> and C<cmp>
use C</$variable/o>.)
As a special case, specifying a PATTERN of space (C<' '>) will split on
-white space just as C<split> with no arguments does. Thus, C<split(' ')> can
+white space just as C<split()> with no arguments does. Thus, C<split(' ')> can
be used to emulate B<awk>'s default behavior, whereas C<split(/ /)>
will give you as many null initial fields as there are leading spaces.
-A C<split> on C</\s+/> is like a C<split(' ')> except that any leading
-whitespace produces a null first field. A C<split> with no arguments
+A C<split()> on C</\s+/> is like a C<split(' ')> except that any leading
+whitespace produces a null first field. A C<split()> with no arguments
really does a C<split(' ', $_)> internally.
Example:
=item sprintf FORMAT, LIST
-Returns a string formatted by the usual C<printf> conventions of the
+Returns a string formatted by the usual C<printf()> conventions of the
C library function C<sprintf()>. See L<sprintf(3)> or L<printf(3)>
on your system for an explanation of the general principles.
=item srand
-Sets the random number seed for the C<rand> operator. If EXPR is
+Sets the random number seed for the C<rand()> operator. If EXPR is
omitted, uses a semi-random value based on the current time and process
ID, among other things. In versions of Perl prior to 5.004 the default
seed was just the current C<time()>. This isn't a particularly good seed,
In fact, it's usually not necessary to call C<srand()> at all, because if
it is not called explicitly, it is called implicitly at the first use of
-the C<rand> operator. However, this was not the case in version of Perl
+the C<rand()> operator. However, this was not the case in version of Perl
before 5.004, so if your script will run under older Perl versions, it
should call C<srand()>.
(This works on machines only for which the device number is negative under NFS.)
-In scalar context, C<stat> returns a boolean value indicating success
+In scalar context, C<stat()> returns a boolean value indicating success
or failure, and, if successful, sets the information associated with
the special filehandle C<_>.
run times with and without it to see which runs faster. Those loops
which scan for many short constant strings (including the constant
parts of more complex patterns) will benefit most. You may have only
-one C<study> active at a time -- if you study a different scalar the first
-is "unstudied". (The way C<study> works is this: a linked list of every
+one C<study()> active at a time -- if you study a different scalar the first
+is "unstudied". (The way C<study()> works is this: a linked list of every
character in the string to be searched is made, so we know, for
example, where all the C<'k'> characters are. From each search string,
the rarest character is selected, based on some static frequency tables
first place.
Note that if you have to look for strings that you don't know till
-runtime, you can build an entire loop as a string and C<eval> that to
+runtime, you can build an entire loop as a string and C<eval()> that to
avoid recompiling all your patterns all the time. Together with
undefining C<$/> to input entire files as one record, this can be very
fast, often faster than specialized programs like C<fgrep(1)>. The following
which in practice should usually suffice.
Syscall returns whatever value returned by the system call it calls.
-If the system call fails, C<syscall> returns C<-1> and sets C<$!> (errno).
+If the system call fails, C<syscall()> returns C<-1> and sets C<$!> (errno).
Note that some system calls can legitimately return C<-1>. The proper
way to handle such calls is to assign C<$!=0;> before the call and
check the value of C<$!> if syscall returns C<-1>.
There's a problem with C<syscall(&SYS_pipe)>: it returns the file
number of the read end of the pipe it creates. There is no way
to retrieve the file number of the other end. You can avoid this
-problem by using C<pipe> instead.
+problem by using C<pipe()> instead.
=item sysopen FILEHANDLE,FILENAME,MODE
Opens the file whose filename is given by FILENAME, and associates it
with FILEHANDLE. If FILEHANDLE is an expression, its value is used as
the name of the real filehandle wanted. This function calls the
-underlying operating system's C<open> function with the parameters
+underlying operating system's C<open()> function with the parameters
FILENAME, MODE, PERMS.
The possible values and flag bits of the MODE parameter are
However, for historical reasons, some values are universal: zero means
read-only, one means write-only, and two means read/write.
-If the file named by FILENAME does not exist and the C<open> call creates
+If the file named by FILENAME does not exist and the C<open()> call creates
it (typically because MODE includes the C<O_CREAT> flag), then the value of
PERMS specifies the permissions of the newly created file. If you omit
-the PERMS argument to C<sysopen>, Perl uses the octal value C<0666>.
+the PERMS argument to C<sysopen()>, Perl uses the octal value C<0666>.
These permission values need to be in octal, and are modified by your
process's current C<umask>. The C<umask> value is a number representing
disabled permissions bits--if your C<umask> were C<027> (group can't write;
-others can't read, write, or execute), then passing C<sysopen> C<0666> would
+others can't read, write, or execute), then passing C<sysopen()> C<0666> would
create a file with mode C<0640> (C<0666 &~ 027> is C<0640>).
-If you find this C<umask> talk confusing, here's some advice: supply a
+If you find this C<umask()> talk confusing, here's some advice: supply a
creation mode of C<0666> for regular files and one of C<0777> for directories
-(in C<mkdir>) and executable files. This gives users the freedom of
+(in C<mkdir()>) and executable files. This gives users the freedom of
choice: if they want protected files, they might choose process umasks
of C<022>, C<027>, or even the particularly antisocial mask of C<077>. Programs
should rarely if ever make policy decisions better left to the user.
The exception to this is when writing files that should be kept private:
mail files, web browser cookies, I<.rhosts> files, and so on. In short,
-seldom if ever use C<0644> as argument to C<sysopen> because that takes
+seldom if ever use C<0644> as argument to C<sysopen()> because that takes
away the user's option to have a more permissive umask. Better to omit it.
The C<IO::File> module provides a more object-oriented approach, if you're
This function binds a variable to a package class that will provide the
implementation for the variable. VARIABLE is the name of the variable
to be enchanted. CLASSNAME is the name of a class implementing objects
-of correct type. Any additional arguments are passed to the "C<new>"
+of correct type. Any additional arguments are passed to the "C<new()>"
method of the class (meaning C<TIESCALAR>, C<TIEARRAY>, or C<TIEHASH>).
Typically these are arguments such as might be passed to the C<dbm_open()>
-function of C. The object returned by the "C<new>" method is also
+function of C. The object returned by the "C<new()>" method is also
returned by the C<tie()> function, which would be useful if you want to
access other methods in CLASSNAME.
unlink @goners;
unlink <*.bak>;
-Note: C<unlink> will not delete directories unless you are superuser and
+Note: C<unlink()> will not delete directories unless you are superuser and
the B<-U> flag is supplied to Perl. Even if these conditions are
met, be warned that unlinking a directory can inflict damage on your
-filesystem. Use C<rmdir> instead.
+filesystem. Use C<rmdir()> instead.
If LIST is omitted, uses C<$_>.
=item unpack TEMPLATE,EXPR
-C<Unpack> does the reverse of C<pack>: it takes a string representing a
+C<Unpack()> does the reverse of C<pack()>: it takes a string representing a
structure and expands it out into a list value, returning the array
value. (In scalar context, it returns merely the first value
-produced.) The TEMPLATE has the same format as in the C<pack> function.
+produced.) The TEMPLATE has the same format as in the C<pack()> function.
Here's a subroutine that does substring:
sub substr {
=item unshift ARRAY,LIST
-Does the opposite of a C<shift>. Or the opposite of a C<push>,
+Does the opposite of a C<shift()>. Or the opposite of a C<push()>,
depending on how you look at it. Prepends list to the front of the
array, and returns the new number of elements in the array.
unshift(ARGV, '-e') unless $ARGV[0] =~ /^-/;
Note the LIST is prepended whole, not one element at a time, so the
-prepended elements stay in the same order. Use C<reverse> to do the
+prepended elements stay in the same order. Use C<reverse()> to do the
reverse.
=item use Module LIST
incompatible ways from older versions of Perl. (We try not to do
this more than we have to.)
-The C<BEGIN> forces the C<require> and C<import> to happen at compile time. The
+The C<BEGIN> forces the C<require> and C<import()> to happen at compile time. The
C<require> makes sure the module is loaded into memory if it hasn't been
-yet. The C<import> is not a builtin--it's just an ordinary static method
+yet. The C<import()> is not a builtin--it's just an ordinary static method
call into the "C<Module>" package to tell the module to import the list of
features back into the current package. The module can implement its
-C<import> method any way it likes, though most modules just choose to
-derive their C<import> method via inheritance from the C<Exporter> class that
-is defined in the C<Exporter> module. See L<Exporter>. If no C<import>
+C<import()> method any way it likes, though most modules just choose to
+derive their C<import()> method via inheritance from the C<Exporter> class that
+is defined in the C<Exporter> module. See L<Exporter>. If no C<import()>
method can be found then the error is currently silently ignored. This
may change to a fatal error in a future version.
through the end of the file).
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>.
+by C<use>, i.e., it calls C<unimport Module LIST> instead of C<import()>.
no integer;
no strict 'refs';
-If no C<unimport> method can be found the call fails with a fatal error.
+If no C<unimport()> method can be found the call fails with a fatal error.
See L<perlmod> for a list of standard modules and pragmas.
If FILEHANDLE is unspecified, output goes to the current default output
channel, which starts out as STDOUT but may be changed by the
-C<select> operator. If the FILEHANDLE is an EXPR, then the expression
+C<select()> operator. If the FILEHANDLE is an EXPR, then the expression
is evaluated and the resulting string is used to look up the name of
the FILEHANDLE at run time. For more on formats, see L<perlform>.
-Note that write is I<NOT> the opposite of C<read>. Unfortunately.
+Note that write is I<NOT> the opposite of C<read()>. Unfortunately.
=item y///
projects / p5sagit/p5-mst-13.2.git / commitdiff