preg_match and UTF-8 in PHP

user_4321 0
Viewed 73743

I'm trying to search a UTF8-encoded string using preg_match.

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

This should print 1, since "H" is at index 1 in the string "¡Hola!". But it prints 2. So it seems like it's not treating the subject as a UTF8-encoded string, even though I'm passing the "u" modifier in the regular expression.

I have the following settings in my php.ini, and other UTF8 functions are working:

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

Any ideas?

utf-8 pcre unicode php
8 Answers

You can calculate the real UTF-8 offset by cutting the string to the offset returned by the preg_mach with the byte-counting substr and then measuring this prefix with the correct-counting mb_strlen.

$utf8Offset = mb_strlen(substr($text, 0, $offsetFromPregMatch), 'UTF-8');
user_8785140

You might want to look at T-Regx library.

pattern('/Hola/u')->match('\xC2\xA1Hola!')->first(function (Match $match) 
{
    echo $match->offset();     // characters
    echo $match->byteOffset(); // bytes
});

This $match->offset() is UTF-8 safe offset.

user_34290150
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