PHP中的preg_match和UTF-8

Question

我正在尝试使用preg_match搜索UTF8编码的字符串.

preg_match('/H/u', "\xC2\xA1Hola!", $a_matches, PREG_OFFSET_CAPTURE);
echo $a_matches[0][1];

这应该打印1,因为"H"在字符串"¡Hola!"中的索引1处.但它打印2.所以它似乎并没有将主题视为UTF8编码的字符串,即使我在正则表达式中传递"u" 修饰符.

我在php.ini中有以下设置,其他UTF8函数正在运行:

mbstring.func_overload = 7
mbstring.language = Neutral
mbstring.internal_encoding = UTF-8
mbstring.http_input = pass
mbstring.http_output = pass
mbstring.encoding_translation = Off

有任何想法吗？

Answer 1

尽管u修饰符使得模式和主题都被解释为UTF-8,但捕获的偏移量仍以字节为单位计算.

您可以使用mb_strlen以UTF-8字符而不是字节来获取长度:

$str = "\xC2\xA1Hola!";
preg_match('/H/u', $str, $a_matches, PREG_OFFSET_CAPTURE);
echo mb_strlen(substr($str, 0, $a_matches[0][1]));

Answer 2

尝试在正则表达式之前添加此(*UTF8):

preg_match('(*UTF8)/H/u', "\xC2\xA1Hola!", $a_matches, PREG_OFFSET_CAPTURE);

魔术,感谢http://www.php.net/manual/es/function.preg-match.php#95828中的评论 .

Answer 3

看起来这是一个"功能",请参阅 http://bugs.php.net/bug.php?id=37391

'u'开关只对pcre有意义,PHP本身并不知道它.

从PHP的角度来看,字符串是字节序列,返回字节偏移似乎是合乎逻辑的(我不说"正确").

Answer 4

请原谅我,但可能有人会觉得它很有用:下面的代码既可以作为preg_match和preg_match_all函数的替代,也可以返回UTF8编码字符串的正确偏移的正确匹配.

     mb_internal_encoding('UTF-8');

     /**
     * Returns array of matches in same format as preg_match or preg_match_all
     * @param bool   $matchAll If true, execute preg_match_all, otherwise preg_match
     * @param string $pattern  The pattern to search for, as a string.
     * @param string $subject  The input string.
     * @param int    $offset   The place from which to start the search (in bytes).
     * @return array
     */
    function pregMatchCapture($matchAll, $pattern, $subject, $offset = 0)
    {
        $matchInfo = array();
        $method    = 'preg_match';
        $flag      = PREG_OFFSET_CAPTURE;
        if ($matchAll) {
            $method .= '_all';
        }
        $n = $method($pattern, $subject, $matchInfo, $flag, $offset);
        $result = array();
        if ($n !== 0 && !empty($matchInfo)) {
            if (!$matchAll) {
                $matchInfo = array($matchInfo);
            }
            foreach ($matchInfo as $matches) {
                $positions = array();
                foreach ($matches as $match) {
                    $matchedText   = $match[0];
                    $matchedLength = $match[1];
                    $positions[]   = array(
                        $matchedText,
                        mb_strlen(mb_strcut($subject, 0, $matchedLength))
                    );
                }
                $result[] = $positions;
            }
            if (!$matchAll) {
                $result = $result[0];
            }
        }
        return $result;
    }

    $s1 = '????????? ??????? ?????? ??? ?????';
    $s2 = 'Try english string for test';

    var_dump(pregMatchCapture(true, '/???/', $s1));
    var_dump(pregMatchCapture(false, '/???/', $s1));

    var_dump(pregMatchCapture(true, '/lish/', $s2));
    var_dump(pregMatchCapture(false, '/lish/', $s2));

我的例子输出:

    array(1) {
      [0]=>
      array(1) {
        [0]=>
        array(2) {
          [0]=>
          string(6) "???"
          [1]=>
          int(4)
        }
      }
    }
    array(1) {
      [0]=>
      array(2) {
        [0]=>
        string(6) "???"
        [1]=>
        int(4)
      }
    }
    array(1) {
      [0]=>
      array(1) {
        [0]=>
        array(2) {
          [0]=>
          string(4) "lish"
          [1]=>
          int(7)
        }
      }
    }
    array(1) {
      [0]=>
      array(2) {
        [0]=>
        string(4) "lish"
        [1]=>
        int(7)
      }
    }