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1 | =head1 NAME |
2 | |
3 | perlrecharclass - Perl Regular Expression Character Classes |
4 | |
5 | =head1 DESCRIPTION |
6 | |
7 | The top level documentation about Perl regular expressions |
8 | is found in L<perlre>. |
9 | |
10 | This manual page discusses the syntax and use of character |
11 | classes in Perl Regular Expressions. |
12 | |
13 | A character class is a way of denoting a set of characters, |
14 | in such a way that one character of the set is matched. |
15 | It's important to remember that matching a character class |
16 | consumes exactly one character in the source string. (The source |
17 | string is the string the regular expression is matched against.) |
18 | |
19 | There are three types of character classes in Perl regular |
20 | expressions: the dot, backslashed sequences, and the bracketed form. |
21 | |
22 | =head2 The dot |
23 | |
24 | The dot (or period), C<.> is probably the most used, and certainly |
25 | the most well-known character class. By default, a dot matches any |
26 | character, except for the newline. The default can be changed to |
27 | add matching the newline with the I<single line> modifier: either |
28 | for the entire regular expression using the C</s> modifier, or |
29 | locally using C<(?s)>. |
30 | |
31 | Here are some examples: |
32 | |
33 | "a" =~ /./ # Match |
34 | "." =~ /./ # Match |
35 | "" =~ /./ # No match (dot has to match a character) |
36 | "\n" =~ /./ # No match (dot does not match a newline) |
37 | "\n" =~ /./s # Match (global 'single line' modifier) |
38 | "\n" =~ /(?s:.)/ # Match (local 'single line' modifier) |
39 | "ab" =~ /^.$/ # No match (dot matches one character) |
40 | |
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41 | =head2 Backslashed sequences |
42 | |
43 | Perl regular expressions contain many backslashed sequences that |
44 | constitute a character class. That is, they will match a single |
45 | character, if that character belongs to a specific set of characters |
46 | (defined by the sequence). A backslashed sequence is a sequence of |
47 | characters starting with a backslash. Not all backslashed sequences |
48 | are character class; for a full list, see L<perlrebackslash>. |
49 | |
50 | Here's a list of the backslashed sequences, which are discussed in |
51 | more detail below. |
52 | |
53 | \d Match a digit character. |
54 | \D Match a non-digit character. |
55 | \w Match a "word" character. |
56 | \W Match a non-"word" character. |
57 | \s Match a white space character. |
58 | \S Match a non-white space character. |
59 | \h Match a horizontal white space character. |
60 | \H Match a character that isn't horizontal white space. |
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61 | \N Match a character that isn't newline. |
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62 | \v Match a vertical white space character. |
63 | \V Match a character that isn't vertical white space. |
64 | \pP, \p{Prop} Match a character matching a Unicode property. |
65 | \PP, \P{Prop} Match a character that doesn't match a Unicode property. |
66 | |
67 | =head3 Digits |
68 | |
69 | C<\d> matches a single character that is considered to be a I<digit>. |
70 | What is considered a digit depends on the internal encoding of |
71 | the source string. If the source string is in UTF-8 format, C<\d> |
72 | not only matches the digits '0' - '9', but also Arabic, Devanagari and |
73 | digits from other languages. Otherwise, if there is a locale in effect, |
74 | it will match whatever characters the locale considers digits. Without |
75 | a locale, C<\d> matches the digits '0' to '9'. |
76 | See L</Locale, Unicode and UTF-8>. |
77 | |
78 | Any character that isn't matched by C<\d> will be matched by C<\D>. |
79 | |
80 | =head3 Word characters |
81 | |
82 | C<\w> matches a single I<word> character: an alphanumeric character |
83 | (that is, an alphabetic character, or a digit), or the underscore (C<_>). |
84 | What is considered a word character depends on the internal encoding |
85 | of the string. If it's in UTF-8 format, C<\w> matches those characters |
86 | that are considered word characters in the Unicode database. That is, it |
87 | not only matches ASCII letters, but also Thai letters, Greek letters, etc. |
88 | If the source string isn't in UTF-8 format, C<\w> matches those characters |
89 | that are considered word characters by the current locale. Without |
90 | a locale in effect, C<\w> matches the ASCII letters, digits and the |
91 | underscore. |
92 | |
93 | Any character that isn't matched by C<\w> will be matched by C<\W>. |
94 | |
95 | =head3 White space |
96 | |
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97 | C<\s> matches any single character that is considered white space. In the |
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98 | ASCII range, C<\s> matches the horizontal tab (C<\t>), the new line |
99 | (C<\n>), the form feed (C<\f>), the carriage return (C<\r>), and the |
100 | space (the vertical tab, C<\cK> is not matched by C<\s>). The exact set |
101 | of characters matched by C<\s> depends on whether the source string is |
102 | in UTF-8 format. If it is, C<\s> matches what is considered white space |
103 | in the Unicode database. Otherwise, if there is a locale in effect, C<\s> |
104 | matches whatever is considered white space by the current locale. Without |
105 | a locale, C<\s> matches the five characters mentioned in the beginning |
106 | of this paragraph. Perhaps the most notable difference is that C<\s> |
107 | matches a non-breaking space only if the non-breaking space is in a |
108 | UTF-8 encoded string. |
109 | |
110 | Any character that isn't matched by C<\s> will be matched by C<\S>. |
111 | |
112 | C<\h> will match any character that is considered horizontal white space; |
113 | this includes the space and the tab characters. C<\H> will match any character |
114 | that is not considered horizontal white space. |
115 | |
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116 | C<\N>, like the dot, will match any character that is not a newline. The |
117 | difference is that C<\N> will not be influenced by the single line C</s> |
118 | regular expression modifier. (Note that, since C<\N{}> is also used for |
119 | Unicode named characters, if C<\N> is followed by an opening brace and |
120 | by a letter, perl will assume that a Unicode character name is coming.) |
121 | |
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122 | C<\v> will match any character that is considered vertical white space; |
123 | this includes the carriage return and line feed characters (newline). |
124 | C<\V> will match any character that is not considered vertical white space. |
125 | |
126 | C<\R> matches anything that can be considered a newline under Unicode |
127 | rules. It's not a character class, as it can match a multi-character |
128 | sequence. Therefore, it cannot be used inside a bracketed character |
129 | class. Details are discussed in L<perlrebackslash>. |
130 | |
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131 | C<\h>, C<\H>, C<\v>, C<\V>, and C<\R> are new in perl 5.10.0. |
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132 | |
133 | Note that unlike C<\s>, C<\d> and C<\w>, C<\h> and C<\v> always match |
134 | the same characters, regardless whether the source string is in UTF-8 |
135 | format or not. The set of characters they match is also not influenced |
136 | by locale. |
137 | |
138 | One might think that C<\s> is equivalent with C<[\h\v]>. This is not true. |
139 | The vertical tab (C<"\x0b">) is not matched by C<\s>, it is however |
140 | considered vertical white space. Furthermore, if the source string is |
141 | not in UTF-8 format, the next line (C<"\x85">) and the no-break space |
142 | (C<"\xA0">) are not matched by C<\s>, but are by C<\v> and C<\h> respectively. |
143 | If the source string is in UTF-8 format, both the next line and the |
144 | no-break space are matched by C<\s>. |
145 | |
146 | The following table is a complete listing of characters matched by |
147 | C<\s>, C<\h> and C<\v>. |
148 | |
149 | The first column gives the code point of the character (in hex format), |
150 | the second column gives the (Unicode) name. The third column indicates |
151 | by which class(es) the character is matched. |
152 | |
153 | 0x00009 CHARACTER TABULATION h s |
154 | 0x0000a LINE FEED (LF) vs |
155 | 0x0000b LINE TABULATION v |
156 | 0x0000c FORM FEED (FF) vs |
157 | 0x0000d CARRIAGE RETURN (CR) vs |
158 | 0x00020 SPACE h s |
159 | 0x00085 NEXT LINE (NEL) vs [1] |
160 | 0x000a0 NO-BREAK SPACE h s [1] |
161 | 0x01680 OGHAM SPACE MARK h s |
162 | 0x0180e MONGOLIAN VOWEL SEPARATOR h s |
163 | 0x02000 EN QUAD h s |
164 | 0x02001 EM QUAD h s |
165 | 0x02002 EN SPACE h s |
166 | 0x02003 EM SPACE h s |
167 | 0x02004 THREE-PER-EM SPACE h s |
168 | 0x02005 FOUR-PER-EM SPACE h s |
169 | 0x02006 SIX-PER-EM SPACE h s |
170 | 0x02007 FIGURE SPACE h s |
171 | 0x02008 PUNCTUATION SPACE h s |
172 | 0x02009 THIN SPACE h s |
173 | 0x0200a HAIR SPACE h s |
174 | 0x02028 LINE SEPARATOR vs |
175 | 0x02029 PARAGRAPH SEPARATOR vs |
176 | 0x0202f NARROW NO-BREAK SPACE h s |
177 | 0x0205f MEDIUM MATHEMATICAL SPACE h s |
178 | 0x03000 IDEOGRAPHIC SPACE h s |
179 | |
180 | =over 4 |
181 | |
182 | =item [1] |
183 | |
184 | NEXT LINE and NO-BREAK SPACE only match C<\s> if the source string is in |
185 | UTF-8 format. |
186 | |
187 | =back |
188 | |
189 | It is worth noting that C<\d>, C<\w>, etc, match single characters, not |
190 | complete numbers or words. To match a number (that consists of integers), |
191 | use C<\d+>; to match a word, use C<\w+>. |
192 | |
193 | |
194 | =head3 Unicode Properties |
195 | |
196 | C<\pP> and C<\p{Prop}> are character classes to match characters that |
197 | fit given Unicode classes. One letter classes can be used in the C<\pP> |
198 | form, with the class name following the C<\p>, otherwise, the property |
199 | name is enclosed in braces, and follows the C<\p>. For instance, a |
200 | match for a number can be written as C</\pN/> or as C</\p{Number}/>. |
201 | Lowercase letters are matched by the property I<LowercaseLetter> which |
202 | has as short form I<Ll>. They have to be written as C</\p{Ll}/> or |
203 | C</\p{LowercaseLetter}/>. C</\pLl/> is valid, but means something different. |
204 | It matches a two character string: a letter (Unicode property C<\pL>), |
205 | followed by a lowercase C<l>. |
206 | |
207 | For a list of possible properties, see |
208 | L<perlunicode/Unicode Character Properties>. It is also possible to |
209 | defined your own properties. This is discussed in |
210 | L<perlunicode/User-Defined Character Properties>. |
211 | |
212 | |
213 | =head4 Examples |
214 | |
215 | "a" =~ /\w/ # Match, "a" is a 'word' character. |
216 | "7" =~ /\w/ # Match, "7" is a 'word' character as well. |
217 | "a" =~ /\d/ # No match, "a" isn't a digit. |
218 | "7" =~ /\d/ # Match, "7" is a digit. |
219 | " " =~ /\s/ # Match, a space is white space. |
220 | "a" =~ /\D/ # Match, "a" is a non-digit. |
221 | "7" =~ /\D/ # No match, "7" is not a non-digit. |
222 | " " =~ /\S/ # No match, a space is not non-white space. |
223 | |
224 | " " =~ /\h/ # Match, space is horizontal white space. |
225 | " " =~ /\v/ # No match, space is not vertical white space. |
226 | "\r" =~ /\v/ # Match, a return is vertical white space. |
227 | |
228 | "a" =~ /\pL/ # Match, "a" is a letter. |
229 | "a" =~ /\p{Lu}/ # No match, /\p{Lu}/ matches upper case letters. |
230 | |
231 | "\x{0e0b}" =~ /\p{Thai}/ # Match, \x{0e0b} is the character |
232 | # 'THAI CHARACTER SO SO', and that's in |
233 | # Thai Unicode class. |
234 | "a" =~ /\P{Lao}/ # Match, as "a" is not a Laoian character. |
235 | |
236 | |
237 | =head2 Bracketed Character Classes |
238 | |
239 | The third form of character class you can use in Perl regular expressions |
240 | is the bracketed form. In its simplest form, it lists the characters |
241 | that may be matched inside square brackets, like this: C<[aeiou]>. |
242 | This matches one of C<a>, C<e>, C<i>, C<o> or C<u>. Just as the other |
243 | character classes, exactly one character will be matched. To match |
244 | a longer string consisting of characters mentioned in the characters |
245 | class, follow the character class with a quantifier. For instance, |
246 | C<[aeiou]+> matches a string of one or more lowercase ASCII vowels. |
247 | |
248 | Repeating a character in a character class has no |
249 | effect; it's considered to be in the set only once. |
250 | |
251 | Examples: |
252 | |
253 | "e" =~ /[aeiou]/ # Match, as "e" is listed in the class. |
254 | "p" =~ /[aeiou]/ # No match, "p" is not listed in the class. |
255 | "ae" =~ /^[aeiou]$/ # No match, a character class only matches |
256 | # a single character. |
257 | "ae" =~ /^[aeiou]+$/ # Match, due to the quantifier. |
258 | |
259 | =head3 Special Characters Inside a Bracketed Character Class |
260 | |
261 | Most characters that are meta characters in regular expressions (that |
262 | is, characters that carry a special meaning like C<*> or C<(>) lose |
263 | their special meaning and can be used inside a character class without |
264 | the need to escape them. For instance, C<[()]> matches either an opening |
265 | parenthesis, or a closing parenthesis, and the parens inside the character |
266 | class don't group or capture. |
267 | |
268 | Characters that may carry a special meaning inside a character class are: |
269 | C<\>, C<^>, C<->, C<[> and C<]>, and are discussed below. They can be |
270 | escaped with a backslash, although this is sometimes not needed, in which |
271 | case the backslash may be omitted. |
272 | |
273 | The sequence C<\b> is special inside a bracketed character class. While |
274 | outside the character class C<\b> is an assertion indicating a point |
275 | that does not have either two word characters or two non-word characters |
276 | on either side, inside a bracketed character class, C<\b> matches a |
277 | backspace character. |
278 | |
279 | A C<[> is not special inside a character class, unless it's the start |
280 | of a POSIX character class (see below). It normally does not need escaping. |
281 | |
282 | A C<]> is either the end of a POSIX character class (see below), or it |
283 | signals the end of the bracketed character class. Normally it needs |
284 | escaping if you want to include a C<]> in the set of characters. |
285 | However, if the C<]> is the I<first> (or the second if the first |
286 | character is a caret) character of a bracketed character class, it |
287 | does not denote the end of the class (as you cannot have an empty class) |
288 | and is considered part of the set of characters that can be matched without |
289 | escaping. |
290 | |
291 | Examples: |
292 | |
293 | "+" =~ /[+?*]/ # Match, "+" in a character class is not special. |
294 | "\cH" =~ /[\b]/ # Match, \b inside in a character class |
295 | # is equivalent with a backspace. |
296 | "]" =~ /[][]/ # Match, as the character class contains. |
297 | # both [ and ]. |
298 | "[]" =~ /[[]]/ # Match, the pattern contains a character class |
299 | # containing just ], and the character class is |
300 | # followed by a ]. |
301 | |
302 | =head3 Character Ranges |
303 | |
304 | It is not uncommon to want to match a range of characters. Luckily, instead |
305 | of listing all the characters in the range, one may use the hyphen (C<->). |
306 | If inside a bracketed character class you have two characters separated |
307 | by a hyphen, it's treated as if all the characters between the two are in |
308 | the class. For instance, C<[0-9]> matches any ASCII digit, and C<[a-m]> |
309 | matches any lowercase letter from the first half of the ASCII alphabet. |
310 | |
311 | Note that the two characters on either side of the hyphen are not |
312 | necessary both letters or both digits. Any character is possible, |
313 | although not advisable. C<['-?]> contains a range of characters, but |
314 | most people will not know which characters that will be. Furthermore, |
315 | such ranges may lead to portability problems if the code has to run on |
316 | a platform that uses a different character set, such as EBCDIC. |
317 | |
318 | If a hyphen in a character class cannot be part of a range, for instance |
319 | because it is the first or the last character of the character class, |
320 | or if it immediately follows a range, the hyphen isn't special, and will be |
321 | considered a character that may be matched. You have to escape the hyphen |
322 | with a backslash if you want to have a hyphen in your set of characters to |
323 | be matched, and its position in the class is such that it can be considered |
324 | part of a range. |
325 | |
326 | Examples: |
327 | |
328 | [a-z] # Matches a character that is a lower case ASCII letter. |
329 | [a-fz] # Matches any letter between 'a' and 'f' (inclusive) or the |
330 | # letter 'z'. |
331 | [-z] # Matches either a hyphen ('-') or the letter 'z'. |
332 | [a-f-m] # Matches any letter between 'a' and 'f' (inclusive), the |
333 | # hyphen ('-'), or the letter 'm'. |
334 | ['-?] # Matches any of the characters '()*+,-./0123456789:;<=>? |
335 | # (But not on an EBCDIC platform). |
336 | |
337 | |
338 | =head3 Negation |
339 | |
340 | It is also possible to instead list the characters you do not want to |
341 | match. You can do so by using a caret (C<^>) as the first character in the |
342 | character class. For instance, C<[^a-z]> matches a character that is not a |
343 | lowercase ASCII letter. |
344 | |
345 | This syntax make the caret a special character inside a bracketed character |
346 | class, but only if it is the first character of the class. So if you want |
347 | to have the caret as one of the characters you want to match, you either |
348 | have to escape the caret, or not list it first. |
349 | |
350 | Examples: |
351 | |
352 | "e" =~ /[^aeiou]/ # No match, the 'e' is listed. |
353 | "x" =~ /[^aeiou]/ # Match, as 'x' isn't a lowercase vowel. |
354 | "^" =~ /[^^]/ # No match, matches anything that isn't a caret. |
355 | "^" =~ /[x^]/ # Match, caret is not special here. |
356 | |
357 | =head3 Backslash Sequences |
358 | |
359 | You can put a backslash sequence character class inside a bracketed character |
360 | class, and it will act just as if you put all the characters matched by |
361 | the backslash sequence inside the character class. For instance, |
362 | C<[a-f\d]> will match any digit, or any of the lowercase letters between |
363 | 'a' and 'f' inclusive. |
364 | |
365 | Examples: |
366 | |
367 | /[\p{Thai}\d]/ # Matches a character that is either a Thai |
368 | # character, or a digit. |
369 | /[^\p{Arabic}()]/ # Matches a character that is neither an Arabic |
370 | # character, nor a parenthesis. |
371 | |
372 | Backslash sequence character classes cannot form one of the endpoints |
373 | of a range. |
374 | |
375 | =head3 Posix Character Classes |
376 | |
377 | Posix character classes have the form C<[:class:]>, where I<class> is |
378 | name, and the C<[:> and C<:]> delimiters. Posix character classes appear |
379 | I<inside> bracketed character classes, and are a convenient and descriptive |
380 | way of listing a group of characters. Be careful about the syntax, |
381 | |
382 | # Correct: |
383 | $string =~ /[[:alpha:]]/ |
384 | |
385 | # Incorrect (will warn): |
386 | $string =~ /[:alpha:]/ |
387 | |
388 | The latter pattern would be a character class consisting of a colon, |
389 | and the letters C<a>, C<l>, C<p> and C<h>. |
390 | |
391 | Perl recognizes the following POSIX character classes: |
392 | |
393 | alpha Any alphabetical character. |
394 | alnum Any alphanumerical character. |
395 | ascii Any ASCII character. |
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396 | blank A GNU extension, equal to a space or a horizontal tab ("\t"). |
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397 | cntrl Any control character. |
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398 | digit Any digit, equivalent to "\d". |
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399 | graph Any printable character, excluding a space. |
400 | lower Any lowercase character. |
401 | print Any printable character, including a space. |
402 | punct Any punctuation character. |
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403 | space Any white space character. "\s" plus the vertical tab ("\cK"). |
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404 | upper Any uppercase character. |
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405 | word Any "word" character, equivalent to "\w". |
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406 | xdigit Any hexadecimal digit, '0' - '9', 'a' - 'f', 'A' - 'F'. |
407 | |
408 | The exact set of characters matched depends on whether the source string |
409 | is internally in UTF-8 format or not. See L</Locale, Unicode and UTF-8>. |
410 | |
411 | Most POSIX character classes have C<\p> counterparts. The difference |
412 | is that the C<\p> classes will always match according to the Unicode |
413 | properties, regardless whether the string is in UTF-8 format or not. |
414 | |
415 | The following table shows the relation between POSIX character classes |
416 | and the Unicode properties: |
417 | |
418 | [[:...:]] \p{...} backslash |
419 | |
420 | alpha IsAlpha |
421 | alnum IsAlnum |
422 | ascii IsASCII |
423 | blank |
424 | cntrl IsCntrl |
425 | digit IsDigit \d |
426 | graph IsGraph |
427 | lower IsLower |
428 | print IsPrint |
429 | punct IsPunct |
430 | space IsSpace |
431 | IsSpacePerl \s |
432 | upper IsUpper |
433 | word IsWord |
434 | xdigit IsXDigit |
435 | |
436 | Some character classes may have a non-obvious name: |
437 | |
438 | =over 4 |
439 | |
440 | =item cntrl |
441 | |
442 | Any control character. Usually, control characters don't produce output |
443 | as such, but instead control the terminal somehow: for example newline |
444 | and backspace are control characters. All characters with C<ord()> less |
445 | than 32 are usually classified as control characters (in ASCII, the ISO |
446 | Latin character sets, and Unicode), as is the character C<ord()> value |
447 | of 127 (C<DEL>). |
448 | |
449 | =item graph |
450 | |
451 | Any character that is I<graphical>, that is, visible. This class consists |
452 | of all the alphanumerical characters and all punctuation characters. |
453 | |
454 | =item print |
455 | |
456 | All printable characters, which is the set of all the graphical characters |
457 | plus the space. |
458 | |
459 | =item punct |
460 | |
461 | Any punctuation (special) character. |
462 | |
463 | =back |
464 | |
465 | =head4 Negation |
466 | |
467 | A Perl extension to the POSIX character class is the ability to |
468 | negate it. This is done by prefixing the class name with a caret (C<^>). |
469 | Some examples: |
470 | |
471 | POSIX Unicode Backslash |
472 | [[:^digit:]] \P{IsDigit} \D |
473 | [[:^space:]] \P{IsSpace} \S |
474 | [[:^word:]] \P{IsWord} \W |
475 | |
476 | =head4 [= =] and [. .] |
477 | |
478 | Perl will recognize the POSIX character classes C<[=class=]>, and |
479 | C<[.class.]>, but does not (yet?) support this construct. Use of |
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480 | such a construct will lead to an error. |
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481 | |
482 | |
483 | =head4 Examples |
484 | |
485 | /[[:digit:]]/ # Matches a character that is a digit. |
486 | /[01[:lower:]]/ # Matches a character that is either a |
487 | # lowercase letter, or '0' or '1'. |
488 | /[[:digit:][:^xdigit:]]/ # Matches a character that can be anything, |
489 | # but the letters 'a' to 'f' in either case. |
490 | # This is because the character class contains |
491 | # all digits, and anything that isn't a |
492 | # hex digit, resulting in a class containing |
493 | # all characters, but the letters 'a' to 'f' |
494 | # and 'A' to 'F'. |
495 | |
496 | |
497 | =head2 Locale, Unicode and UTF-8 |
498 | |
499 | Some of the character classes have a somewhat different behaviour depending |
500 | on the internal encoding of the source string, and the locale that is |
501 | in effect. |
502 | |
503 | C<\w>, C<\d>, C<\s> and the POSIX character classes (and their negations, |
504 | including C<\W>, C<\D>, C<\S>) suffer from this behaviour. |
505 | |
506 | The rule is that if the source string is in UTF-8 format, the character |
507 | classes match according to the Unicode properties. If the source string |
508 | isn't, then the character classes match according to whatever locale is |
509 | in effect. If there is no locale, they match the ASCII defaults |
510 | (52 letters, 10 digits and underscore for C<\w>, 0 to 9 for C<\d>, etc). |
511 | |
512 | This usually means that if you are matching against characters whose C<ord()> |
513 | values are between 128 and 255 inclusive, your character class may match |
514 | or not depending on the current locale, and whether the source string is |
515 | in UTF-8 format. The string will be in UTF-8 format if it contains |
516 | characters whose C<ord()> value exceeds 255. But a string may be in UTF-8 |
517 | format without it having such characters. |
518 | |
519 | For portability reasons, it may be better to not use C<\w>, C<\d>, C<\s> |
520 | or the POSIX character classes, and use the Unicode properties instead. |
521 | |
522 | =head4 Examples |
523 | |
524 | $str = "\xDF"; # $str is not in UTF-8 format. |
525 | $str =~ /^\w/; # No match, as $str isn't in UTF-8 format. |
526 | $str .= "\x{0e0b}"; # Now $str is in UTF-8 format. |
527 | $str =~ /^\w/; # Match! $str is now in UTF-8 format. |
528 | chop $str; |
529 | $str =~ /^\w/; # Still a match! $str remains in UTF-8 format. |
530 | |
531 | =cut |