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1 | =head1 NAME |
2 | ||
07fcf8ff | 3 | perluniintro - Perl Unicode introduction |
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4 | |
5 | =head1 DESCRIPTION | |
6 | ||
7 | This document gives a general idea of Unicode and how to use Unicode | |
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8 | in Perl. See L</Further Resources> for references to more in-depth |
9 | treatments of Unicode. | |
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10 | |
11 | =head2 Unicode | |
12 | ||
376d9008 | 13 | Unicode is a character set standard which plans to codify all of the |
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14 | writing systems of the world, plus many other symbols. |
15 | ||
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16 | Unicode and ISO/IEC 10646 are coordinated standards that unify |
17 | almost all other modern character set standards, | |
18 | covering more than 80 writing systems and hundreds of languages, | |
376d9008 | 19 | including all commercially-important modern languages. All characters |
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20 | in the largest Chinese, Japanese, and Korean dictionaries are also |
21 | encoded. The standards will eventually cover almost all characters in | |
22 | more than 250 writing systems and thousands of languages. | |
c8695642 | 23 | Unicode 1.0 was released in October 1991, and 6.0 in October 2010. |
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24 | |
25 | A Unicode I<character> is an abstract entity. It is not bound to any | |
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26 | particular integer width, especially not to the C language C<char>. |
27 | Unicode is language-neutral and display-neutral: it does not encode the | |
e1b711da | 28 | language of the text, and it does not generally define fonts or other graphical |
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29 | layout details. Unicode operates on characters and on text built from |
30 | those characters. | |
31 | ||
32 | Unicode defines characters like C<LATIN CAPITAL LETTER A> or C<GREEK | |
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33 | SMALL LETTER ALPHA> and unique numbers for the characters, in this |
34 | case 0x0041 and 0x03B1, respectively. These unique numbers are called | |
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35 | I<code points>. A code point is essentially the position of the |
36 | character within the set of all possible Unicode characters, and thus in | |
37 | Perl, the term I<ordinal> is often used interchangeably with it. | |
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38 | |
39 | The Unicode standard prefers using hexadecimal notation for the code | |
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40 | points. If numbers like C<0x0041> are unfamiliar to you, take a peek |
41 | at a later section, L</"Hexadecimal Notation">. The Unicode standard | |
42 | uses the notation C<U+0041 LATIN CAPITAL LETTER A>, to give the | |
43 | hexadecimal code point and the normative name of the character. | |
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44 | |
45 | Unicode also defines various I<properties> for the characters, like | |
376d9008 | 46 | "uppercase" or "lowercase", "decimal digit", or "punctuation"; |
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47 | these properties are independent of the names of the characters. |
48 | Furthermore, various operations on the characters like uppercasing, | |
376d9008 | 49 | lowercasing, and collating (sorting) are defined. |
ba62762e | 50 | |
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51 | A Unicode I<logical> "character" can actually consist of more than one internal |
52 | I<actual> "character" or code point. For Western languages, this is adequately | |
c670e63a | 53 | modelled by a I<base character> (like C<LATIN CAPITAL LETTER A>) followed |
0111a78f | 54 | by one or more I<modifiers> (like C<COMBINING ACUTE ACCENT>). This sequence of |
376d9008 | 55 | base character and modifiers is called a I<combining character |
0111a78f | 56 | sequence>. Some non-western languages require more complicated |
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57 | models, so Unicode created the I<grapheme cluster> concept, which was |
58 | later further refined into the I<extended grapheme cluster>. For | |
59 | example, a Korean Hangul syllable is considered a single logical | |
60 | character, but most often consists of three actual | |
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61 | Unicode characters: a leading consonant followed by an interior vowel followed |
62 | by a trailing consonant. | |
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63 | |
64 | Whether to call these extended grapheme clusters "characters" depends on your | |
65 | point of view. If you are a programmer, you probably would tend towards seeing | |
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66 | each element in the sequences as one unit, or "character". However from |
67 | the user's point of view, the whole sequence could be seen as one | |
68 | "character" since that's probably what it looks like in the context of the | |
69 | user's language. In this document, we take the programmer's point of | |
70 | view: one "character" is one Unicode code point. | |
71 | ||
72 | For some combinations of base character and modifiers, there are | |
73 | I<precomposed> characters. There is a single character equivalent, for | |
74 | example, to the sequence C<LATIN CAPITAL LETTER A> followed by | |
75 | C<COMBINING ACUTE ACCENT>. It is called C<LATIN CAPITAL LETTER A WITH | |
76 | ACUTE>. These precomposed characters are, however, only available for | |
77 | some combinations, and are mainly meant to support round-trip | |
78 | conversions between Unicode and legacy standards (like ISO 8859). Using | |
79 | sequences, as Unicode does, allows for needing fewer basic building blocks | |
80 | (code points) to express many more potential grapheme clusters. To | |
81 | support conversion between equivalent forms, various I<normalization | |
82 | forms> are also defined. Thus, C<LATIN CAPITAL LETTER A WITH ACUTE> is | |
83 | in I<Normalization Form Composed>, (abbreviated NFC), and the sequence | |
84 | C<LATIN CAPITAL LETTER A> followed by C<COMBINING ACUTE ACCENT> | |
85 | represents the same character in I<Normalization Form Decomposed> (NFD). | |
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86 | |
87 | Because of backward compatibility with legacy encodings, the "a unique | |
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88 | number for every character" idea breaks down a bit: instead, there is |
89 | "at least one number for every character". The same character could | |
90 | be represented differently in several legacy encodings. The | |
35146e33 | 91 | converse is not also true: some code points do not have an assigned |
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92 | character. Firstly, there are unallocated code points within |
93 | otherwise used blocks. Secondly, there are special Unicode control | |
94 | characters that do not represent true characters. | |
ba62762e | 95 | |
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96 | When Unicode was first conceived, it was thought that all the world's |
97 | characters could be represented using a 16-bit word; that is a maximum of | |
98 | C<0x10000> (or 65536) characters from C<0x0000> to C<0xFFFF> would be | |
99 | needed. This soon proved to be false, and since Unicode 2.0 (July | |
4c496f0c | 100 | 1996), Unicode has been defined all the way up to 21 bits (C<0x10FFFF>), |
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101 | and Unicode 3.1 (March 2001) defined the first characters above C<0xFFFF>. |
102 | The first C<0x10000> characters are called the I<Plane 0>, or the | |
103 | I<Basic Multilingual Plane> (BMP). With Unicode 3.1, 17 (yes, | |
104 | seventeen) planes in all were defined--but they are nowhere near full of | |
105 | defined characters, yet. | |
106 | ||
107 | When a new language is being encoded, Unicode generally will choose a | |
108 | C<block> of consecutive unallocated code points for its characters. So | |
109 | far, the number of code points in these blocks has always been evenly | |
110 | divisible by 16. Extras in a block, not currently needed, are left | |
111 | unallocated, for future growth. But there have been occasions when | |
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112 | a later relase needed more code points than the available extras, and a |
113 | new block had to allocated somewhere else, not contiguous to the initial | |
114 | one, to handle the overflow. Thus, it became apparent early on that | |
115 | "block" wasn't an adequate organizing principal, and so the C<Script> | |
116 | property was created. (Later an improved script property was added as | |
117 | well, the C<Script_Extensions> property.) Those code points that are in | |
118 | overflow blocks can still | |
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119 | have the same script as the original ones. The script concept fits more |
120 | closely with natural language: there is C<Latin> script, C<Greek> | |
121 | script, and so on; and there are several artificial scripts, like | |
122 | C<Common> for characters that are used in multiple scripts, such as | |
123 | mathematical symbols. Scripts usually span varied parts of several | |
124 | blocks. For more information about scripts, see L<perlunicode/Scripts>. | |
1bfb14c4 | 125 | The division into blocks exists, but it is almost completely |
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126 | accidental--an artifact of how the characters have been and still are |
127 | allocated. (Note that this paragraph has oversimplified things for the | |
128 | sake of this being an introduction. Unicode doesn't really encode | |
129 | languages, but the writing systems for them--their scripts; and one | |
130 | script can be used by many languages. Unicode also encodes things that | |
131 | aren't really about languages, such as symbols like C<BAGGAGE CLAIM>.) | |
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132 | |
133 | The Unicode code points are just abstract numbers. To input and | |
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134 | output these abstract numbers, the numbers must be I<encoded> or |
135 | I<serialised> somehow. Unicode defines several I<character encoding | |
136 | forms>, of which I<UTF-8> is perhaps the most popular. UTF-8 is a | |
137 | variable length encoding that encodes Unicode characters as 1 to 6 | |
e1b711da | 138 | bytes. Other encodings |
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139 | include UTF-16 and UTF-32 and their big- and little-endian variants |
140 | (UTF-8 is byte-order independent) The ISO/IEC 10646 defines the UCS-2 | |
141 | and UCS-4 encoding forms. | |
ba62762e | 142 | |
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143 | For more information about encodings--for instance, to learn what |
144 | I<surrogates> and I<byte order marks> (BOMs) are--see L<perlunicode>. | |
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145 | |
146 | =head2 Perl's Unicode Support | |
147 | ||
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148 | Starting from Perl 5.6.0, Perl has had the capacity to handle Unicode |
149 | natively. Perl 5.8.0, however, is the first recommended release for | |
150 | serious Unicode work. The maintenance release 5.6.1 fixed many of the | |
151 | problems of the initial Unicode implementation, but for example | |
1bfb14c4 | 152 | regular expressions still do not work with Unicode in 5.6.1. |
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153 | Perl 5.14.0 is the first release where Unicode support is |
154 | (almost) seamlessly integrable without some gotchas (the exception being | |
155 | some differences in L<quotemeta|perlfunc/quotemeta>). To enable this | |
156 | seamless support, you should C<use feature 'unicode_strings'> (which is | |
157 | automatically selected if you C<use 5.012> or higher). See L<feature>. | |
158 | (5.14 also fixes a number of bugs and departures from the Unicode | |
159 | standard.) | |
160 | ||
161 | Before Perl 5.8.0, the use of C<use utf8> was used to declare | |
ba62762e | 162 | that operations in the current block or file would be Unicode-aware. |
376d9008 | 163 | This model was found to be wrong, or at least clumsy: the "Unicodeness" |
1bfb14c4 | 164 | is now carried with the data, instead of being attached to the |
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165 | operations. |
166 | Starting with Perl 5.8.0, only one case remains where an explicit C<use | |
167 | utf8> is needed: if your Perl script itself is encoded in UTF-8, you can | |
168 | use UTF-8 in your identifier names, and in string and regular expression | |
376d9008 | 169 | literals, by saying C<use utf8>. This is not the default because |
8f8cf39c | 170 | scripts with legacy 8-bit data in them would break. See L<utf8>. |
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171 | |
172 | =head2 Perl's Unicode Model | |
173 | ||
376d9008 | 174 | Perl supports both pre-5.6 strings of eight-bit native bytes, and |
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175 | strings of Unicode characters. The general principle is that Perl tries |
176 | to keep its data as eight-bit bytes for as long as possible, but as soon | |
177 | as Unicodeness cannot be avoided, the data is transparently upgraded | |
178 | to Unicode. Prior to Perl 5.14, the upgrade was not completely | |
179 | transparent (see L<perlunicode/The "Unicode Bug">), and for backwards | |
180 | compatibility, full transparency is not gained unless C<use feature | |
181 | 'unicode_strings'> (see L<feature>) or C<use 5.012> (or higher) is | |
182 | selected. | |
ba62762e | 183 | |
4192de81 | 184 | Internally, Perl currently uses either whatever the native eight-bit |
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185 | character set of the platform (for example Latin-1) is, defaulting to |
186 | UTF-8, to encode Unicode strings. Specifically, if all code points in | |
187 | the string are C<0xFF> or less, Perl uses the native eight-bit | |
188 | character set. Otherwise, it uses UTF-8. | |
4192de81 | 189 | |
7ca610e8 | 190 | A user of Perl does not normally need to know nor care how Perl |
20ba30f4 | 191 | happens to encode its internal strings, but it becomes relevant when |
ac036724 | 192 | outputting Unicode strings to a stream without a PerlIO layer (one with |
193 | the "default" encoding). In such a case, the raw bytes used internally | |
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194 | (the native character set or UTF-8, as appropriate for each string) |
195 | will be used, and a "Wide character" warning will be issued if those | |
196 | strings contain a character beyond 0x00FF. | |
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197 | |
198 | For example, | |
199 | ||
ae5648b3 | 200 | perl -e 'print "\x{DF}\n", "\x{0100}\x{DF}\n"' |
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201 | |
202 | produces a fairly useless mixture of native bytes and UTF-8, as well | |
1bfb14c4 | 203 | as a warning: |
4192de81 | 204 | |
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205 | Wide character in print at ... |
206 | ||
740d4bb2 | 207 | To output UTF-8, use the C<:encoding> or C<:utf8> output layer. Prepending |
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208 | |
209 | binmode(STDOUT, ":utf8"); | |
210 | ||
376d9008 | 211 | to this sample program ensures that the output is completely UTF-8, |
1bfb14c4 | 212 | and removes the program's warning. |
ba62762e | 213 | |
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214 | You can enable automatic UTF-8-ification of your standard file |
215 | handles, default C<open()> layer, and C<@ARGV> by using either | |
216 | the C<-C> command line switch or the C<PERL_UNICODE> environment | |
217 | variable, see L<perlrun> for the documentation of the C<-C> switch. | |
218 | ||
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219 | Note that this means that Perl expects other software to work the same |
220 | way: | |
8aa8f774 | 221 | if Perl has been led to believe that STDIN should be UTF-8, but then |
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222 | STDIN coming in from another command is not UTF-8, Perl will likely |
223 | complain about the malformed UTF-8. | |
b310b053 | 224 | |
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225 | All features that combine Unicode and I/O also require using the new |
226 | PerlIO feature. Almost all Perl 5.8 platforms do use PerlIO, though: | |
227 | you can see whether yours is by running "perl -V" and looking for | |
228 | C<useperlio=define>. | |
229 | ||
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230 | =head2 Unicode and EBCDIC |
231 | ||
232 | Perl 5.8.0 also supports Unicode on EBCDIC platforms. There, | |
376d9008 | 233 | Unicode support is somewhat more complex to implement since |
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234 | additional conversions are needed at every step. |
235 | ||
236 | Later Perl releases have added code that will not work on EBCDIC platforms, and | |
237 | no one has complained, so the divergence has continued. If you want to run | |
238 | Perl on an EBCDIC platform, send email to perlbug@perl.org | |
64c66fb6 | 239 | |
64c66fb6 | 240 | On EBCDIC platforms, the internal Unicode encoding form is UTF-EBCDIC |
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241 | instead of UTF-8. The difference is that as UTF-8 is "ASCII-safe" in |
242 | that ASCII characters encode to UTF-8 as-is, while UTF-EBCDIC is | |
243 | "EBCDIC-safe". | |
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244 | |
245 | =head2 Creating Unicode | |
246 | ||
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247 | To create Unicode characters in literals for code points above C<0xFF>, |
248 | use the C<\x{...}> notation in double-quoted strings: | |
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249 | |
250 | my $smiley = "\x{263a}"; | |
251 | ||
376d9008 | 252 | Similarly, it can be used in regular expression literals |
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253 | |
254 | $smiley =~ /\x{263a}/; | |
255 | ||
256 | At run-time you can use C<chr()>: | |
257 | ||
258 | my $hebrew_alef = chr(0x05d0); | |
259 | ||
376d9008 | 260 | See L</"Further Resources"> for how to find all these numeric codes. |
ba62762e | 261 | |
376d9008 JB |
262 | Naturally, C<ord()> will do the reverse: it turns a character into |
263 | a code point. | |
ba62762e | 264 | |
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265 | Note that C<\x..> (no C<{}> and only two hexadecimal digits), C<\x{...}>, |
266 | and C<chr(...)> for arguments less than C<0x100> (decimal 256) | |
267 | generate an eight-bit character for backward compatibility with older | |
268 | Perls. For arguments of C<0x100> or more, Unicode characters are | |
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269 | always produced. If you want to force the production of Unicode |
270 | characters regardless of the numeric value, use C<pack("U", ...)> | |
271 | instead of C<\x..>, C<\x{...}>, or C<chr()>. | |
ba62762e | 272 | |
fbb93542 | 273 | You can invoke characters |
376d9008 | 274 | by name in double-quoted strings: |
ba62762e | 275 | |
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276 | my $arabic_alef = "\N{ARABIC LETTER ALEF}"; |
277 | ||
278 | And, as mentioned above, you can also C<pack()> numbers into Unicode | |
279 | characters: | |
280 | ||
281 | my $georgian_an = pack("U", 0x10a0); | |
282 | ||
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283 | Note that both C<\x{...}> and C<\N{...}> are compile-time string |
284 | constants: you cannot use variables in them. if you want similar | |
fb121860 | 285 | run-time functionality, use C<chr()> and C<charnames::string_vianame()>. |
8a5e5dd5 | 286 | |
1eda90df | 287 | If you want to force the result to Unicode characters, use the special |
f337b084 TH |
288 | C<"U0"> prefix. It consumes no arguments but causes the following bytes |
289 | to be interpreted as the UTF-8 encoding of Unicode characters: | |
1eda90df | 290 | |
f337b084 | 291 | my $chars = pack("U0W*", 0x80, 0x42); |
771cd3b2 | 292 | |
ae5648b3 | 293 | Likewise, you can stop such UTF-8 interpretation by using the special |
771cd3b2 | 294 | C<"C0"> prefix. |
1eda90df | 295 | |
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296 | =head2 Handling Unicode |
297 | ||
298 | Handling Unicode is for the most part transparent: just use the | |
299 | strings as usual. Functions like C<index()>, C<length()>, and | |
300 | C<substr()> will work on the Unicode characters; regular expressions | |
301 | will work on the Unicode characters (see L<perlunicode> and L<perlretut>). | |
302 | ||
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303 | Note that Perl considers grapheme clusters to be separate characters, so for |
304 | example | |
ba62762e | 305 | |
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306 | print length("\N{LATIN CAPITAL LETTER A}\N{COMBINING ACUTE ACCENT}"), |
307 | "\n"; | |
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308 | |
309 | will print 2, not 1. The only exception is that regular expressions | |
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310 | have C<\X> for matching an extended grapheme cluster. (Thus C<\X> in a |
311 | regular expression would match the entire sequence of both the example | |
312 | characters.) | |
ba62762e | 313 | |
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314 | Life is not quite so transparent, however, when working with legacy |
315 | encodings, I/O, and certain special cases: | |
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316 | |
317 | =head2 Legacy Encodings | |
318 | ||
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319 | When you combine legacy data and Unicode, the legacy data needs |
320 | to be upgraded to Unicode. Normally the legacy data is assumed to be | |
321 | ISO 8859-1 (or EBCDIC, if applicable). | |
ba62762e | 322 | |
376d9008 | 323 | The C<Encode> module knows about many encodings and has interfaces |
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324 | for doing conversions between those encodings: |
325 | ||
2c9359a2 RGS |
326 | use Encode 'decode'; |
327 | $data = decode("iso-8859-3", $data); # convert from legacy to utf-8 | |
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328 | |
329 | =head2 Unicode I/O | |
330 | ||
8baee566 | 331 | Normally, writing out Unicode data |
ba62762e | 332 | |
8baee566 | 333 | print FH $some_string_with_unicode, "\n"; |
ba62762e | 334 | |
8baee566 | 335 | produces raw bytes that Perl happens to use to internally encode the |
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336 | Unicode string. Perl's internal encoding depends on the system as |
337 | well as what characters happen to be in the string at the time. If | |
338 | any of the characters are at code points C<0x100> or above, you will get | |
339 | a warning. To ensure that the output is explicitly rendered in the | |
340 | encoding you desire--and to avoid the warning--open the stream with | |
341 | the desired encoding. Some examples: | |
ba62762e | 342 | |
ec90690f TS |
343 | open FH, ">:utf8", "file"; |
344 | ||
345 | open FH, ">:encoding(ucs2)", "file"; | |
346 | open FH, ">:encoding(UTF-8)", "file"; | |
347 | open FH, ">:encoding(shift_jis)", "file"; | |
1d7919c5 | 348 | |
376d9008 | 349 | and on already open streams, use C<binmode()>: |
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350 | |
351 | binmode(STDOUT, ":utf8"); | |
352 | ||
ec90690f TS |
353 | binmode(STDOUT, ":encoding(ucs2)"); |
354 | binmode(STDOUT, ":encoding(UTF-8)"); | |
355 | binmode(STDOUT, ":encoding(shift_jis)"); | |
356 | ||
b5d8778e | 357 | The matching of encoding names is loose: case does not matter, and |
fae2c0fb | 358 | many encodings have several aliases. Note that the C<:utf8> layer |
1bfb14c4 | 359 | must always be specified exactly like that; it is I<not> subject to |
c8695642 | 360 | the loose matching of encoding names. Also note that currently C<:utf8> is unsafe for |
740d4bb2 | 361 | input, because it accepts the data without validating that it is indeed valid |
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362 | UTF-8; you should instead use C<:encoding(utf-8)> (with or without a |
363 | hyphen). | |
b5d8778e | 364 | |
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365 | See L<PerlIO> for the C<:utf8> layer, L<PerlIO::encoding> and |
366 | L<Encode::PerlIO> for the C<:encoding()> layer, and | |
367 | L<Encode::Supported> for many encodings supported by the C<Encode> | |
368 | module. | |
ba62762e | 369 | |
a5f0baef | 370 | Reading in a file that you know happens to be encoded in one of the |
1bfb14c4 JH |
371 | Unicode or legacy encodings does not magically turn the data into |
372 | Unicode in Perl's eyes. To do that, specify the appropriate | |
fae2c0fb | 373 | layer when opening files |
ba62762e | 374 | |
740d4bb2 | 375 | open(my $fh,'<:encoding(utf8)', 'anything'); |
8baee566 JF |
376 | my $line_of_unicode = <$fh>; |
377 | ||
ec90690f | 378 | open(my $fh,'<:encoding(Big5)', 'anything'); |
8baee566 | 379 | my $line_of_unicode = <$fh>; |
ba62762e | 380 | |
fae2c0fb | 381 | The I/O layers can also be specified more flexibly with |
376d9008 | 382 | the C<open> pragma. See L<open>, or look at the following example. |
ba62762e | 383 | |
9e5bbba0 KW |
384 | use open ':encoding(utf8)'; # input/output default encoding will be |
385 | # UTF-8 | |
1d7919c5 JH |
386 | open X, ">file"; |
387 | print X chr(0x100), "\n"; | |
ba62762e | 388 | close X; |
1d7919c5 | 389 | open Y, "<file"; |
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390 | printf "%#x\n", ord(<Y>); # this should print 0x100 |
391 | close Y; | |
392 | ||
fae2c0fb | 393 | With the C<open> pragma you can use the C<:locale> layer |
ba62762e | 394 | |
12f98225 | 395 | BEGIN { $ENV{LC_ALL} = $ENV{LANG} = 'ru_RU.KOI8-R' } |
9e5bbba0 KW |
396 | # the :locale will probe the locale environment variables like |
397 | # LC_ALL | |
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398 | use open OUT => ':locale'; # russki parusski |
399 | open(O, ">koi8"); | |
400 | print O chr(0x430); # Unicode CYRILLIC SMALL LETTER A = KOI8-R 0xc1 | |
401 | close O; | |
402 | open(I, "<koi8"); | |
403 | printf "%#x\n", ord(<I>), "\n"; # this should print 0xc1 | |
404 | close I; | |
405 | ||
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406 | These methods install a transparent filter on the I/O stream that |
407 | converts data from the specified encoding when it is read in from the | |
a5f0baef | 408 | stream. The result is always Unicode. |
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409 | |
410 | The L<open> pragma affects all the C<open()> calls after the pragma by | |
fae2c0fb RGS |
411 | setting default layers. If you want to affect only certain |
412 | streams, use explicit layers directly in the C<open()> call. | |
ba62762e JH |
413 | |
414 | You can switch encodings on an already opened stream by using | |
8baee566 | 415 | C<binmode()>; see L<perlfunc/binmode>. |
ba62762e | 416 | |
1ecefa54 JH |
417 | The C<:locale> does not currently (as of Perl 5.8.0) work with |
418 | C<open()> and C<binmode()>, only with the C<open> pragma. The | |
8baee566 | 419 | C<:utf8> and C<:encoding(...)> methods do work with all of C<open()>, |
1ecefa54 | 420 | C<binmode()>, and the C<open> pragma. |
ba62762e | 421 | |
fae2c0fb | 422 | Similarly, you may use these I/O layers on output streams to |
a5f0baef JH |
423 | automatically convert Unicode to the specified encoding when it is |
424 | written to the stream. For example, the following snippet copies the | |
425 | contents of the file "text.jis" (encoded as ISO-2022-JP, aka JIS) to | |
426 | the file "text.utf8", encoded as UTF-8: | |
ba62762e | 427 | |
c722ef0a JH |
428 | open(my $nihongo, '<:encoding(iso-2022-jp)', 'text.jis'); |
429 | open(my $unicode, '>:utf8', 'text.utf8'); | |
0cf8a8d9 | 430 | while (<$nihongo>) { print $unicode $_ } |
ba62762e JH |
431 | |
432 | The naming of encodings, both by the C<open()> and by the C<open> | |
2575c402 JW |
433 | pragma allows for flexible names: C<koi8-r> and C<KOI8R> will both be |
434 | understood. | |
ba62762e JH |
435 | |
436 | Common encodings recognized by ISO, MIME, IANA, and various other | |
8baee566 | 437 | standardisation organisations are recognised; for a more detailed |
1bfb14c4 | 438 | list see L<Encode::Supported>. |
ba62762e JH |
439 | |
440 | C<read()> reads characters and returns the number of characters. | |
441 | C<seek()> and C<tell()> operate on byte counts, as do C<sysread()> | |
442 | and C<sysseek()>. | |
443 | ||
8baee566 | 444 | Notice that because of the default behaviour of not doing any |
fae2c0fb | 445 | conversion upon input if there is no default layer, |
ba62762e | 446 | it is easy to mistakenly write code that keeps on expanding a file |
1bfb14c4 | 447 | by repeatedly encoding the data: |
ba62762e JH |
448 | |
449 | # BAD CODE WARNING | |
450 | open F, "file"; | |
8baee566 | 451 | local $/; ## read in the whole file of 8-bit characters |
ba62762e JH |
452 | $t = <F>; |
453 | close F; | |
740d4bb2 | 454 | open F, ">:encoding(utf8)", "file"; |
8baee566 | 455 | print F $t; ## convert to UTF-8 on output |
ba62762e JH |
456 | close F; |
457 | ||
458 | If you run this code twice, the contents of the F<file> will be twice | |
740d4bb2 JW |
459 | UTF-8 encoded. A C<use open ':encoding(utf8)'> would have avoided the |
460 | bug, or explicitly opening also the F<file> for input as UTF-8. | |
ba62762e | 461 | |
0c901d84 | 462 | B<NOTE>: the C<:utf8> and C<:encoding> features work only if your |
d0fadae5 JH |
463 | Perl has been built with the new PerlIO feature (which is the default |
464 | on most systems). | |
0c901d84 | 465 | |
1ecefa54 JH |
466 | =head2 Displaying Unicode As Text |
467 | ||
468 | Sometimes you might want to display Perl scalars containing Unicode as | |
8baee566 | 469 | simple ASCII (or EBCDIC) text. The following subroutine converts |
1ecefa54 | 470 | its argument so that Unicode characters with code points greater than |
1bfb14c4 JH |
471 | 255 are displayed as C<\x{...}>, control characters (like C<\n>) are |
472 | displayed as C<\x..>, and the rest of the characters as themselves: | |
1ecefa54 | 473 | |
9e5bbba0 KW |
474 | sub nice_string { |
475 | join("", | |
476 | map { $_ > 255 ? # if wide character... | |
477 | sprintf("\\x{%04X}", $_) : # \x{...} | |
9ba22424 | 478 | chr($_) =~ /[[:cntrl:]]/ ? # else if control character... |
9e5bbba0 KW |
479 | sprintf("\\x%02X", $_) : # \x.. |
480 | quotemeta(chr($_)) # else quoted or as themselves | |
f337b084 | 481 | } unpack("W*", $_[0])); # unpack Unicode characters |
58c274a1 JF |
482 | } |
483 | ||
484 | For example, | |
485 | ||
486 | nice_string("foo\x{100}bar\n") | |
487 | ||
d0551e73 | 488 | returns the string |
58c274a1 | 489 | |
d0551e73 JH |
490 | 'foo\x{0100}bar\x0A' |
491 | ||
492 | which is ready to be printed. | |
1ecefa54 | 493 | |
ba62762e JH |
494 | =head2 Special Cases |
495 | ||
496 | =over 4 | |
497 | ||
498 | =item * | |
499 | ||
500 | Bit Complement Operator ~ And vec() | |
501 | ||
1bfb14c4 JH |
502 | The bit complement operator C<~> may produce surprising results if |
503 | used on strings containing characters with ordinal values above | |
504 | 255. In such a case, the results are consistent with the internal | |
505 | encoding of the characters, but not with much else. So don't do | |
506 | that. Similarly for C<vec()>: you will be operating on the | |
507 | internally-encoded bit patterns of the Unicode characters, not on | |
508 | the code point values, which is very probably not what you want. | |
ba62762e JH |
509 | |
510 | =item * | |
511 | ||
8baee566 JF |
512 | Peeking At Perl's Internal Encoding |
513 | ||
514 | Normal users of Perl should never care how Perl encodes any particular | |
a5f0baef | 515 | Unicode string (because the normal ways to get at the contents of a |
376d9008 | 516 | string with Unicode--via input and output--should always be via |
fae2c0fb | 517 | explicitly-defined I/O layers). But if you must, there are two |
a5f0baef | 518 | ways of looking behind the scenes. |
ba62762e JH |
519 | |
520 | One way of peeking inside the internal encoding of Unicode characters | |
f337b084 TH |
521 | is to use C<unpack("C*", ...> to get the bytes of whatever the string |
522 | encoding happens to be, or C<unpack("U0..", ...)> to get the bytes of the | |
523 | UTF-8 encoding: | |
ba62762e | 524 | |
8baee566 | 525 | # this prints c4 80 for the UTF-8 bytes 0xc4 0x80 |
f337b084 | 526 | print join(" ", unpack("U0(H2)*", pack("U", 0x100))), "\n"; |
ba62762e JH |
527 | |
528 | Yet another way would be to use the Devel::Peek module: | |
529 | ||
530 | perl -MDevel::Peek -e 'Dump(chr(0x100))' | |
531 | ||
1e54db1a | 532 | That shows the C<UTF8> flag in FLAGS and both the UTF-8 bytes |
376d9008 | 533 | and Unicode characters in C<PV>. See also later in this document |
8800c35a | 534 | the discussion about the C<utf8::is_utf8()> function. |
ba62762e JH |
535 | |
536 | =back | |
537 | ||
538 | =head2 Advanced Topics | |
539 | ||
540 | =over 4 | |
541 | ||
542 | =item * | |
543 | ||
544 | String Equivalence | |
545 | ||
546 | The question of string equivalence turns somewhat complicated | |
376d9008 | 547 | in Unicode: what do you mean by "equal"? |
ba62762e | 548 | |
07698885 RGS |
549 | (Is C<LATIN CAPITAL LETTER A WITH ACUTE> equal to |
550 | C<LATIN CAPITAL LETTER A>?) | |
ba62762e | 551 | |
a5f0baef JH |
552 | The short answer is that by default Perl compares equivalence (C<eq>, |
553 | C<ne>) based only on code points of the characters. In the above | |
376d9008 | 554 | case, the answer is no (because 0x00C1 != 0x0041). But sometimes, any |
c8695642 | 555 | CAPITAL LETTER A's should be considered equal, or even A's of any case. |
ba62762e JH |
556 | |
557 | The long answer is that you need to consider character normalization | |
e1b711da KW |
558 | and casing issues: see L<Unicode::Normalize>, Unicode Technical Report #15, |
559 | L<Unicode Normalization Forms|http://www.unicode.org/unicode/reports/tr15> and | |
560 | sections on case mapping in the L<Unicode Standard|http://www.unicode.org>. | |
ba62762e | 561 | |
1bfb14c4 | 562 | As of Perl 5.8.0, the "Full" case-folding of I<Case |
afba1538 KW |
563 | Mappings/SpecialCasing> is implemented, but bugs remain in C<qr//i> with them, |
564 | mostly fixed by 5.14. | |
ba62762e JH |
565 | |
566 | =item * | |
567 | ||
568 | String Collation | |
569 | ||
376d9008 | 570 | People like to see their strings nicely sorted--or as Unicode |
ba62762e JH |
571 | parlance goes, collated. But again, what do you mean by collate? |
572 | ||
07698885 RGS |
573 | (Does C<LATIN CAPITAL LETTER A WITH ACUTE> come before or after |
574 | C<LATIN CAPITAL LETTER A WITH GRAVE>?) | |
ba62762e | 575 | |
58c274a1 | 576 | The short answer is that by default, Perl compares strings (C<lt>, |
ba62762e | 577 | C<le>, C<cmp>, C<ge>, C<gt>) based only on the code points of the |
1bfb14c4 | 578 | characters. In the above case, the answer is "after", since |
da76a1f4 | 579 | C<0x00C1> > C<0x00C0>. |
ba62762e JH |
580 | |
581 | The long answer is that "it depends", and a good answer cannot be | |
582 | given without knowing (at the very least) the language context. | |
583 | See L<Unicode::Collate>, and I<Unicode Collation Algorithm> | |
2bbc8d55 | 584 | L<http://www.unicode.org/unicode/reports/tr10/> |
ba62762e JH |
585 | |
586 | =back | |
587 | ||
588 | =head2 Miscellaneous | |
589 | ||
590 | =over 4 | |
591 | ||
592 | =item * | |
593 | ||
3ff56b75 | 594 | Character Ranges and Classes |
ba62762e | 595 | |
0eb9ada1 KW |
596 | Character ranges in regular expression bracketed character classes ( e.g., |
597 | C</[a-z]/>) and in the C<tr///> (also known as C<y///>) operator are not | |
598 | magically Unicode-aware. What this means is that C<[A-Za-z]> will not | |
599 | magically start to mean "all alphabetic letters" (not that it does mean that | |
600 | even for 8-bit characters; for those, if you are using locales (L<perllocale>), | |
601 | use C</[[:alpha:]]/>; and if not, use the 8-bit-aware property C<\p{alpha}>). | |
602 | ||
603 | All the properties that begin with C<\p> (and its inverse C<\P>) are actually | |
604 | character classes that are Unicode-aware. There are dozens of them, see | |
605 | L<perluniprops>. | |
606 | ||
607 | You can use Unicode code points as the end points of character ranges, and the | |
608 | range will include all Unicode code points that lie between those end points. | |
ba62762e JH |
609 | |
610 | =item * | |
611 | ||
612 | String-To-Number Conversions | |
613 | ||
376d9008 JB |
614 | Unicode does define several other decimal--and numeric--characters |
615 | besides the familiar 0 to 9, such as the Arabic and Indic digits. | |
ba62762e | 616 | Perl does not support string-to-number conversion for digits other |
58c274a1 | 617 | than ASCII 0 to 9 (and ASCII a to f for hexadecimal). |
c8695642 | 618 | To get safe conversions from any Unicode string, use |
67592e11 | 619 | L<Unicode::UCD/num()>. |
ba62762e JH |
620 | |
621 | =back | |
622 | ||
623 | =head2 Questions With Answers | |
624 | ||
625 | =over 4 | |
626 | ||
818c4caa | 627 | =item * |
5cb3728c RB |
628 | |
629 | Will My Old Scripts Break? | |
ba62762e JH |
630 | |
631 | Very probably not. Unless you are generating Unicode characters | |
1bfb14c4 JH |
632 | somehow, old behaviour should be preserved. About the only behaviour |
633 | that has changed and which could start generating Unicode is the old | |
634 | behaviour of C<chr()> where supplying an argument more than 255 | |
635 | produced a character modulo 255. C<chr(300)>, for example, was equal | |
636 | to C<chr(45)> or "-" (in ASCII), now it is LATIN CAPITAL LETTER I WITH | |
637 | BREVE. | |
ba62762e | 638 | |
818c4caa | 639 | =item * |
5cb3728c RB |
640 | |
641 | How Do I Make My Scripts Work With Unicode? | |
ba62762e JH |
642 | |
643 | Very little work should be needed since nothing changes until you | |
1bfb14c4 JH |
644 | generate Unicode data. The most important thing is getting input as |
645 | Unicode; for that, see the earlier I/O discussion. | |
c8695642 KW |
646 | To get full seamless Unicode support, add |
647 | C<use feature 'unicode_strings'> (or C<use 5.012> or higher) to your | |
648 | script. | |
ba62762e | 649 | |
818c4caa | 650 | =item * |
5cb3728c RB |
651 | |
652 | How Do I Know Whether My String Is In Unicode? | |
ba62762e | 653 | |
c8695642 KW |
654 | You shouldn't have to care. But you may if your Perl is before 5.14.0 |
655 | or you haven't specified C<use feature 'unicode_strings'> or C<use | |
656 | 5.012> (or higher) because otherwise the semantics of the code points | |
657 | in the range 128 to 255 are different depending on | |
2bbc8d55 | 658 | whether the string they are contained within is in Unicode or not. |
e1b711da | 659 | (See L<perlunicode/When Unicode Does Not Happen>.) |
ba62762e | 660 | |
2bbc8d55 | 661 | To determine if a string is in Unicode, use: |
ba62762e | 662 | |
8800c35a | 663 | print utf8::is_utf8($string) ? 1 : 0, "\n"; |
ba62762e JH |
664 | |
665 | But note that this doesn't mean that any of the characters in the | |
666 | string are necessary UTF-8 encoded, or that any of the characters have | |
667 | code points greater than 0xFF (255) or even 0x80 (128), or that the | |
668 | string has any characters at all. All the C<is_utf8()> does is to | |
669 | return the value of the internal "utf8ness" flag attached to the | |
376d9008 | 670 | C<$string>. If the flag is off, the bytes in the scalar are interpreted |
3c1c8017 | 671 | as a single byte encoding. If the flag is on, the bytes in the scalar |
0eb9ada1 KW |
672 | are interpreted as the (variable-length, potentially multi-byte) UTF-8 encoded |
673 | code points of the characters. Bytes added to a UTF-8 encoded string are | |
1e54db1a | 674 | automatically upgraded to UTF-8. If mixed non-UTF-8 and UTF-8 scalars |
c8695642 | 675 | are merged (double-quoted interpolation, explicit concatenation, or |
3c1c8017 AT |
676 | printf/sprintf parameter substitution), the result will be UTF-8 encoded |
677 | as if copies of the byte strings were upgraded to UTF-8: for example, | |
678 | ||
679 | $a = "ab\x80c"; | |
680 | $b = "\x{100}"; | |
681 | print "$a = $b\n"; | |
682 | ||
a02b5feb JH |
683 | the output string will be UTF-8-encoded C<ab\x80c = \x{100}\n>, but |
684 | C<$a> will stay byte-encoded. | |
ba62762e JH |
685 | |
686 | Sometimes you might really need to know the byte length of a string | |
ce7675db | 687 | instead of the character length. For that use either the |
00d823b9 | 688 | C<Encode::encode_utf8()> function or the C<bytes> pragma |
c8695642 | 689 | and the C<length()> function: |
ba62762e JH |
690 | |
691 | my $unicode = chr(0x100); | |
692 | print length($unicode), "\n"; # will print 1 | |
ce7675db | 693 | require Encode; |
9ba22424 | 694 | print length(Encode::encode_utf8($unicode)),"\n"; # will print 2 |
00d823b9 | 695 | use bytes; |
1bfb14c4 JH |
696 | print length($unicode), "\n"; # will also print 2 |
697 | # (the 0xC4 0x80 of the UTF-8) | |
0eb9ada1 | 698 | no bytes; |
ba62762e | 699 | |
818c4caa | 700 | =item * |
5cb3728c | 701 | |
c8695642 KW |
702 | How Do I Find Out What Encoding a File Has? |
703 | ||
968ee499 | 704 | You might try L<Encode::Guess>, but it has a number of limitations. |
c8695642 KW |
705 | |
706 | =item * | |
707 | ||
5cb3728c | 708 | How Do I Detect Data That's Not Valid In a Particular Encoding? |
ba62762e | 709 | |
8baee566 JF |
710 | Use the C<Encode> package to try converting it. |
711 | For example, | |
ba62762e | 712 | |
bb2f379c | 713 | use Encode 'decode_utf8'; |
2bbc8d55 | 714 | |
228ee848 | 715 | if (eval { decode_utf8($string, Encode::FB_CROAK); 1 }) { |
a365f2ce | 716 | # $string is valid utf8 |
ba62762e | 717 | } else { |
a365f2ce | 718 | # $string is not valid utf8 |
ba62762e JH |
719 | } |
720 | ||
f337b084 | 721 | Or use C<unpack> to try decoding it: |
ba62762e JH |
722 | |
723 | use warnings; | |
f337b084 | 724 | @chars = unpack("C0U*", $string_of_bytes_that_I_think_is_utf8); |
ba62762e | 725 | |
ae5648b3 RGS |
726 | If invalid, a C<Malformed UTF-8 character> warning is produced. The "C0" means |
727 | "process the string character per character". Without that, the | |
728 | C<unpack("U*", ...)> would work in C<U0> mode (the default if the format | |
729 | string starts with C<U>) and it would return the bytes making up the UTF-8 | |
f337b084 | 730 | encoding of the target string, something that will always work. |
ba62762e | 731 | |
818c4caa | 732 | =item * |
5cb3728c RB |
733 | |
734 | How Do I Convert Binary Data Into a Particular Encoding, Or Vice Versa? | |
ba62762e | 735 | |
8baee566 JF |
736 | This probably isn't as useful as you might think. |
737 | Normally, you shouldn't need to. | |
ba62762e | 738 | |
1bfb14c4 | 739 | In one sense, what you are asking doesn't make much sense: encodings |
376d9008 | 740 | are for characters, and binary data are not "characters", so converting |
a5f0baef JH |
741 | "data" into some encoding isn't meaningful unless you know in what |
742 | character set and encoding the binary data is in, in which case it's | |
376d9008 | 743 | not just binary data, now is it? |
8baee566 | 744 | |
1bfb14c4 JH |
745 | If you have a raw sequence of bytes that you know should be |
746 | interpreted via a particular encoding, you can use C<Encode>: | |
ba62762e JH |
747 | |
748 | use Encode 'from_to'; | |
749 | from_to($data, "iso-8859-1", "utf-8"); # from latin-1 to utf-8 | |
750 | ||
1bfb14c4 JH |
751 | The call to C<from_to()> changes the bytes in C<$data>, but nothing |
752 | material about the nature of the string has changed as far as Perl is | |
753 | concerned. Both before and after the call, the string C<$data> | |
754 | contains just a bunch of 8-bit bytes. As far as Perl is concerned, | |
755 | the encoding of the string remains as "system-native 8-bit bytes". | |
8baee566 JF |
756 | |
757 | You might relate this to a fictional 'Translate' module: | |
758 | ||
759 | use Translate; | |
760 | my $phrase = "Yes"; | |
761 | Translate::from_to($phrase, 'english', 'deutsch'); | |
762 | ## phrase now contains "Ja" | |
ba62762e | 763 | |
8baee566 | 764 | The contents of the string changes, but not the nature of the string. |
1bfb14c4 JH |
765 | Perl doesn't know any more after the call than before that the |
766 | contents of the string indicates the affirmative. | |
ba62762e | 767 | |
376d9008 | 768 | Back to converting data. If you have (or want) data in your system's |
a5f0baef JH |
769 | native 8-bit encoding (e.g. Latin-1, EBCDIC, etc.), you can use |
770 | pack/unpack to convert to/from Unicode. | |
ba62762e | 771 | |
f337b084 TH |
772 | $native_string = pack("W*", unpack("U*", $Unicode_string)); |
773 | $Unicode_string = pack("U*", unpack("W*", $native_string)); | |
ba62762e JH |
774 | |
775 | If you have a sequence of bytes you B<know> is valid UTF-8, | |
776 | but Perl doesn't know it yet, you can make Perl a believer, too: | |
777 | ||
778 | use Encode 'decode_utf8'; | |
8baee566 | 779 | $Unicode = decode_utf8($bytes); |
ba62762e | 780 | |
f337b084 TH |
781 | or: |
782 | ||
783 | $Unicode = pack("U0a*", $bytes); | |
ae5648b3 | 784 | |
2bbc8d55 SP |
785 | You can find the bytes that make up a UTF-8 sequence with |
786 | ||
9e5bbba0 | 787 | @bytes = unpack("C*", $Unicode_string) |
2bbc8d55 SP |
788 | |
789 | and you can create well-formed Unicode with | |
790 | ||
9e5bbba0 | 791 | $Unicode_string = pack("U*", 0xff, ...) |
ba62762e | 792 | |
818c4caa | 793 | =item * |
5cb3728c RB |
794 | |
795 | How Do I Display Unicode? How Do I Input Unicode? | |
ba62762e | 796 | |
2bbc8d55 SP |
797 | See L<http://www.alanwood.net/unicode/> and |
798 | L<http://www.cl.cam.ac.uk/~mgk25/unicode.html> | |
ba62762e | 799 | |
818c4caa | 800 | =item * |
5cb3728c RB |
801 | |
802 | How Does Unicode Work With Traditional Locales? | |
ba62762e | 803 | |
66cbab2c KW |
804 | Starting in Perl 5.16, you can specify |
805 | ||
806 | use locale ':not_characters'; | |
807 | ||
808 | to get Perl to work well with tradtional locales. The catch is that you | |
809 | have to translate from the locale character set to/from Unicode | |
810 | yourself. See L</Unicode IE<sol>O> above for how to | |
811 | ||
812 | use open ':locale'; | |
813 | ||
814 | to accomplish this, but full details are in L<perllocale/Unicode and | |
815 | UTF-8>, including gotchas that happen if you don't specifiy | |
816 | C<:not_characters>. | |
ba62762e JH |
817 | |
818 | =back | |
819 | ||
820 | =head2 Hexadecimal Notation | |
821 | ||
376d9008 JB |
822 | The Unicode standard prefers using hexadecimal notation because |
823 | that more clearly shows the division of Unicode into blocks of 256 characters. | |
ba62762e JH |
824 | Hexadecimal is also simply shorter than decimal. You can use decimal |
825 | notation, too, but learning to use hexadecimal just makes life easier | |
1bfb14c4 | 826 | with the Unicode standard. The C<U+HHHH> notation uses hexadecimal, |
076d825e | 827 | for example. |
ba62762e JH |
828 | |
829 | The C<0x> prefix means a hexadecimal number, the digits are 0-9 I<and> | |
830 | a-f (or A-F, case doesn't matter). Each hexadecimal digit represents | |
831 | four bits, or half a byte. C<print 0x..., "\n"> will show a | |
832 | hexadecimal number in decimal, and C<printf "%x\n", $decimal> will | |
833 | show a decimal number in hexadecimal. If you have just the | |
376d9008 | 834 | "hex digits" of a hexadecimal number, you can use the C<hex()> function. |
ba62762e JH |
835 | |
836 | print 0x0009, "\n"; # 9 | |
837 | print 0x000a, "\n"; # 10 | |
838 | print 0x000f, "\n"; # 15 | |
839 | print 0x0010, "\n"; # 16 | |
840 | print 0x0011, "\n"; # 17 | |
841 | print 0x0100, "\n"; # 256 | |
842 | ||
843 | print 0x0041, "\n"; # 65 | |
844 | ||
845 | printf "%x\n", 65; # 41 | |
846 | printf "%#x\n", 65; # 0x41 | |
847 | ||
848 | print hex("41"), "\n"; # 65 | |
849 | ||
850 | =head2 Further Resources | |
851 | ||
852 | =over 4 | |
853 | ||
854 | =item * | |
855 | ||
856 | Unicode Consortium | |
857 | ||
2bbc8d55 | 858 | L<http://www.unicode.org/> |
ba62762e JH |
859 | |
860 | =item * | |
861 | ||
862 | Unicode FAQ | |
863 | ||
2bbc8d55 | 864 | L<http://www.unicode.org/unicode/faq/> |
ba62762e JH |
865 | |
866 | =item * | |
867 | ||
868 | Unicode Glossary | |
869 | ||
2bbc8d55 | 870 | L<http://www.unicode.org/glossary/> |
ba62762e JH |
871 | |
872 | =item * | |
873 | ||
c8695642 KW |
874 | Unicode Recommended Reading List |
875 | ||
876 | The Unicode Consortium has a list of articles and books, some of which | |
877 | give a much more in depth treatment of Unicode: | |
878 | L<http://unicode.org/resources/readinglist.html> | |
879 | ||
880 | =item * | |
881 | ||
ba62762e JH |
882 | Unicode Useful Resources |
883 | ||
2bbc8d55 | 884 | L<http://www.unicode.org/unicode/onlinedat/resources.html> |
ba62762e JH |
885 | |
886 | =item * | |
887 | ||
888 | Unicode and Multilingual Support in HTML, Fonts, Web Browsers and Other Applications | |
889 | ||
2bbc8d55 | 890 | L<http://www.alanwood.net/unicode/> |
ba62762e JH |
891 | |
892 | =item * | |
893 | ||
894 | UTF-8 and Unicode FAQ for Unix/Linux | |
895 | ||
2bbc8d55 | 896 | L<http://www.cl.cam.ac.uk/~mgk25/unicode.html> |
ba62762e JH |
897 | |
898 | =item * | |
899 | ||
900 | Legacy Character Sets | |
901 | ||
2bbc8d55 SP |
902 | L<http://www.czyborra.com/> |
903 | L<http://www.eki.ee/letter/> | |
ba62762e JH |
904 | |
905 | =item * | |
906 | ||
ba62762e JH |
907 | You can explore various information from the Unicode data files using |
908 | the C<Unicode::UCD> module. | |
909 | ||
910 | =back | |
911 | ||
f6edf83b JH |
912 | =head1 UNICODE IN OLDER PERLS |
913 | ||
914 | If you cannot upgrade your Perl to 5.8.0 or later, you can still | |
915 | do some Unicode processing by using the modules C<Unicode::String>, | |
916 | C<Unicode::Map8>, and C<Unicode::Map>, available from CPAN. | |
917 | If you have the GNU recode installed, you can also use the | |
376d9008 | 918 | Perl front-end C<Convert::Recode> for character conversions. |
f6edf83b | 919 | |
aaef10c5 | 920 | The following are fast conversions from ISO 8859-1 (Latin-1) bytes |
63de3cb2 | 921 | to UTF-8 bytes and back, the code works even with older Perl 5 versions. |
aaef10c5 JH |
922 | |
923 | # ISO 8859-1 to UTF-8 | |
924 | s/([\x80-\xFF])/chr(0xC0|ord($1)>>6).chr(0x80|ord($1)&0x3F)/eg; | |
925 | ||
926 | # UTF-8 to ISO 8859-1 | |
927 | s/([\xC2\xC3])([\x80-\xBF])/chr(ord($1)<<6&0xC0|ord($2)&0x3F)/eg; | |
928 | ||
ba62762e JH |
929 | =head1 SEE ALSO |
930 | ||
2575c402 | 931 | L<perlunitut>, L<perlunicode>, L<Encode>, L<open>, L<utf8>, L<bytes>, |
4c496f0c JH |
932 | L<perlretut>, L<perlrun>, L<Unicode::Collate>, L<Unicode::Normalize>, |
933 | L<Unicode::UCD> | |
ba62762e | 934 | |
376d9008 | 935 | =head1 ACKNOWLEDGMENTS |
ba62762e JH |
936 | |
937 | Thanks to the kind readers of the perl5-porters@perl.org, | |
938 | perl-unicode@perl.org, linux-utf8@nl.linux.org, and unicore@unicode.org | |
939 | mailing lists for their valuable feedback. | |
940 | ||
941 | =head1 AUTHOR, COPYRIGHT, AND LICENSE | |
942 | ||
c8695642 | 943 | Copyright 2001-2011 Jarkko Hietaniemi E<lt>jhi@iki.fiE<gt> |
ba62762e JH |
944 | |
945 | This document may be distributed under the same terms as Perl itself. |