Provided by: libunicode-string-perl_2.09-5build1_amd64 
NAME
Unicode::String - String of Unicode characters (UTF-16BE)
SYNOPSIS
use Unicode::String qw(utf8 latin1 utf16be);
$u = utf8("string");
$u = latin1("string");
$u = utf16be("\0s\0t\0r\0i\0n\0g");
print $u->utf32be; # 4 byte characters
print $u->utf16le; # 2 byte characters + surrogates
print $u->utf8; # 1-4 byte characters
DESCRIPTION
A "Unicode::String" object represents a sequence of Unicode characters. Methods are provided to convert
between various external formats (encodings) and "Unicode::String" objects, and methods are provided for
common string manipulations.
The functions utf32be(), utf32le(), utf16be(), utf16le(), utf8(), utf7(), latin1(), uhex(), uchr() can be
imported from the "Unicode::String" module and will work as constructors initializing strings of the
corresponding encoding.
The "Unicode::String" objects overload various operators, which means that they in most cases can be
treated like plain strings.
Internally a "Unicode::String" object is represented by a string of 2 byte numbers in network byte order
(big-endian). This representation is not visible by the API provided, but it might be useful to know in
order to predict the efficiency of the provided methods.
METHODS
Class methods
The following class methods are available:
Unicode::String->stringify_as
Unicode::String->stringify_as( $enc )
This method is used to specify which encoding will be used when "Unicode::String" objects are
implicitly converted to and from plain strings.
If an argument is provided it sets the current encoding. The argument should have one of the
following: "ucs4", "utf32", "utf32be", "utf32le", "ucs2", "utf16", "utf16be", "utf16le", "utf8",
"utf7", "latin1" or "hex". The default is "utf8".
The stringify_as() method returns a reference to the current encoding function.
$us = Unicode::String->new
$us = Unicode::String->new( $initial_value )
This is the object constructor. Without argument, it creates an empty "Unicode::String" object. If
an $initial_value argument is given, it is decoded according to the specified stringify_as()
encoding, UTF-8 by default.
In general it is recommended to import and use one of the encoding specific constructor functions
instead of invoking this method.
Encoding methods
These methods get or set the value of the "Unicode::String" object by passing strings in the
corresponding encoding. If a new value is passed as argument it will set the value of the
"Unicode::String", and the previous value is returned. If no argument is passed then the current value
is returned.
To illustrate the encodings we show how the 2 character sample string of "Xm" (micro meter) is encoded
for each one.
$us->utf32be
$us->utf32be( $newval )
The string passed should be in the UTF-32 encoding with bytes in big endian order. The sample "Xm"
is "\0\0\0\xB5\0\0\0m" in this encoding.
Alternative names for this method are utf32() and ucs4().
$us->utf32le
$us->utf32le( $newval )
The string passed should be in the UTF-32 encoding with bytes in little endian order. The sample
"Xm" is is "\xB5\0\0\0m\0\0\0" in this encoding.
$us->utf16be
$us->utf16be( $newval )
The string passed should be in the UTF-16 encoding with bytes in big endian order. The sample "Xm" is
"\0\xB5\0m" in this encoding.
Alternative names for this method are utf16() and ucs2().
If the string passed to utf16be() starts with the Unicode byte order mark in little endian order, the
result is as if utf16le() was called instead.
$us->utf16le
$us->utf16le( $newval )
The string passed should be in the UTF-16 encoding with bytes in little endian order. The sample
"Xm" is is "\xB5\0m\0" in this encoding. This is the encoding used by the Microsoft Windows API.
If the string passed to utf16le() starts with the Unicode byte order mark in big endian order, the
result is as if utf16le() was called instead.
$us->utf8
$us->utf8( $newval )
The string passed should be in the UTF-8 encoding. The sample "Xm" is "\xC2\xB5m" in this encoding.
$us->utf7
$us->utf7( $newval )
The string passed should be in the UTF-7 encoding. The sample "Xm" is "+ALU-m" in this encoding.
The UTF-7 encoding only use plain US-ASCII characters for the encoding. This makes it safe for
transport through 8-bit stripping protocols. Characters outside the US-ASCII range are
base64-encoded and '+' is used as an escape character. The UTF-7 encoding is described in RFC 1642.
If the (global) variable $Unicode::String::UTF7_OPTIONAL_DIRECT_CHARS is TRUE, then a wider range of
characters are encoded as themselves. It is even TRUE by default. The characters affected by this
are:
! " # $ % & * ; < = > @ [ ] ^ _ ` { | }
$us->latin1
$us->latin1( $newval )
The string passed should be in the ISO-8859-1 encoding. The sample "Xm" is "\xB5m" in this encoding.
Characters outside the "\x00" .. "\xFF" range are simply removed from the return value of the
latin1() method. If you want more control over the mapping from Unicode to ISO-8859-1, use the
"Unicode::Map8" class. This is also the way to deal with other 8-bit character sets.
$us->hex
$us->hex( $newval )
The string passed should be plain ASCII where each Unicode character is represented by the "U+XXXX"
string and separated by a single space character. The "U+" prefix is optional when setting the
value. The sample "Xm" is "U+00b5 U+006d" in this encoding.
String Operations
The following methods are available:
$us->as_string
Converts a "Unicode::String" to a plain string according to the setting of stringify_as(). The
default stringify_as() encoding is "utf8".
$us->as_num
Converts a "Unicode::String" to a number. Currently only the digits in the range 0x30 .. 0x39 are
recognized. The plan is to eventually support all Unicode digit characters.
$us->as_bool
Converts a "Unicode::String" to a boolean value. Only the empty string is FALSE. A string
consisting of only the character U+0030 is considered TRUE, even if Perl consider "0" to be FALSE.
$us->repeat( $count )
Returns a new "Unicode::String" where the content of $us is repeated $count times. This operation is
also overloaded as:
$us x $count
$us->concat( $other_string )
Concatenates the string $us and the string $other_string. If $other_string is not an
"Unicode::String" object, then it is first passed to the Unicode::String->new constructor function.
This operation is also overloaded as:
$us . $other_string
$us->append( $other_string )
Appends the string $other_string to the value of $us. If $other_string is not an "Unicode::String"
object, then it is first passed to the Unicode::String->new constructor function. This operation is
also overloaded as:
$us .= $other_string
$us->copy
Returns a copy of the current "Unicode::String" object. This operation is overloaded as the
assignment operator.
$us->length
Returns the length of the "Unicode::String". Surrogate pairs are still counted as 2.
$us->byteswap
This method will swap the bytes in the internal representation of the "Unicode::String" object.
Unicode reserve the character U+FEFF character as a byte order mark. This works because the swapped
character, U+FFFE, is reserved to not be valid. For strings that have the byte order mark as the
first character, we can guaranty to get the byte order right with the following code:
$ustr->byteswap if $ustr->ord == 0xFFFE;
$us->unpack
Returns a list of integers each representing an UCS-2 character code.
$us->pack( @uchr )
Sets the value of $us as a sequence of UCS-2 characters with the characters codes given as parameter.
$us->ord
Returns the character code of the first character in $us. The ord() method deals with surrogate
pairs, which gives us a result-range of 0x0 .. 0x10FFFF. If the $us string is empty, undef is
returned.
$us->chr( $code )
Sets the value of $us to be a string containing the character assigned code $code. The argument
$code must be an integer in the range 0x0 .. 0x10FFFF. If the code is greater than 0xFFFF then a
surrogate pair created.
$us->name
In scalar context returns the official Unicode name of the first character in $us. In array context
returns the name of all characters in $us. Also see Unicode::CharName.
$us->substr( $offset )
$us->substr( $offset, $length )
$us->substr( $offset, $length, $subst )
Returns a sub-string of $us. Works similar to the builtin substr() function.
$us->index( $other )
$us->index( $other, $pos )
Locates the position of $other within $us, possibly starting the search at position $pos.
$us->chop
Chops off the last character of $us and returns it (as a "Unicode::String" object).
FUNCTIONS
The following functions are provided. None of these are exported by default.
byteswap2( $str, ... )
This function will swap 2 and 2 bytes in the strings passed as arguments. If this function is called
in void context, then it will modify its arguments in-place. Otherwise, the swapped strings are
returned.
byteswap4( $str, ... )
The byteswap4 function works similar to byteswap2, but will reverse the order of 4 and 4 bytes.
latin1( $str )
utf7( $str )
utf8( $str )
utf16le( $str )
utf16be( $str )
utf32le( $str )
utf32be( $str )
Constructor functions for the various Unicode encodings. These return new "Unicode::String" objects.
The provided argument should be encoded correspondingly.
uhex( $str )
Constructs a new "Unicode::String" object from a string of hex values. See hex() method above for
description of the format.
uchar( $num )
Constructs a new one character "Unicode::String" object from a Unicode character code. This works
similar to perl's builtin chr() function.
SEE ALSO
Unicode::CharName, Unicode::Map8
<http://www.unicode.org/>
perlunicode
COPYRIGHT
Copyright 1997-2000,2005 Gisle Aas.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl
itself.
POD ERRORS
Hey! The above document had some coding errors, which are explained below:
Around line 600:
Non-ASCII character seen before =encoding in '"Xm"'. Assuming ISO8859-1
perl v5.18.1 2005-10-26 String(3pm)