mb_ereg

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

mb_ereg — Búsqueda por expresión regular con soporte para caracteres multibyte

Descripción

mb_ereg(string $pattern, string $string, array &$matches = null): bool

Búsqueda por expresión regular con soporte para caracteres multibyte.

Parámetros

pattern

El patrón de búsqueda.

string

La cadena sobre la que se realiza la búsqueda.

matches

Si se encuentran coincidencias para las subcadenas entre paréntesis de pattern y si la función es llamada con el tercer argumento matches, las coincidencias serán almacenadas en los elementos del array matches. Si no se encuentra ninguna coincidencia, matches tendrá como valor un array vacío.

$matches[1] contendrá la subcadena que comienza en la primera paréntesis izquierdo; $matches[2] contendrá la subcadena que comienza en la segunda, y así sucesivamente. $matches[0] contendrá una copia de la cadena completa coincidente.

Valores devueltos

Devuelve si se ha encontrado una coincidencia de pattern en string.

Historial de cambios

Versión	Descripción
8.0.0	Esta función devuelve ahora `true` en caso de éxito. Anteriormente, devolvía la longitud en bytes de la cadena encontrada, si se encontraba una coincidencia para `pattern` en `string` y si se proporcionaba `matches`. Si el parámetro opcional `matches` no se proporcionaba o si la longitud de la cadena coincidente era `0`, esta función devolvía `1`.
7.1.0	mb_ereg() ahora asignará `matches` a un array vacío, si no hay coincidencias. Anteriormente, los `matches` no se modificaban en este caso.

Notas

Nota:
The internal encoding or the character encoding specified by mb_regex_encoding() will be used as the character encoding for this function.

Ver también

mb_regex_encoding() - Define/Recupera la codificación de caracteres para las expresiones regulares multioctetos
mb_eregi() - Expresión regular insensible a mayúsculas/minúsculas con soporte para caracteres multioctetos

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User Contributed Notes 12 notes

down

Anonymous ¶

4 years ago

One of the differences between preg_match() & mb_ereg()
about "captured parenthesized subpattern".

<?php

preg_match('/(abc)(.*)/', 'abc', $match);
var_dump($match);

mb_ereg('(abc)(.*)', 'abc', $match);
var_dump($match);

?>

array(3) {
  [0]=>
  string(3) "abc"
  [1]=>
  string(3) "abc"
  [2]=>
  string(0) ""       // <-- "string"(0) "" : preg_match()
}

array(3) {
  [0]=>
  string(3) "abc"
  [1]=>
  string(3) "abc"
  [2]=>
  bool(false)       // <-- "bool"(false) : mb_ereg()
}

down

Anonymous ¶

8 years ago

Old link to Oniguruma regex syntax is not working anymore, there is a working one:
https://github.com/geoffgarside/oniguruma/blob/master/Syntax.txt

down

pressler at hotmail dot de ¶

12 years ago

Note that mb_ereg() does not support the \uFFFF unicode syntax but uses \x{FFFF} instead:

<?PHP

$text = 'Peter is a boy.'; // english
$text = 'بيتر هو صبي.'; // arabic
//$text = 'פיטר הוא ילד.'; // hebrew

mb_regex_encoding('UTF-8');

if(mb_ereg('[\x{0600}-\x{06FF}]', $text)) // arabic range
//if(mb_ereg('[\x{0590}-\x{05FF}]', $text)) // hebrew range
{
    echo "Text has some arabic/hebrew characters.";
}
else
{
    echo "Text doesnt have arabic/hebrew characters.";
}

?>

down

Anonymous ¶

1 year ago

mb_ereg() cannot match over 100,000 (100K) characters (not bytes but characters)
whereas preg_match() can over 1,000,000,000 (1G, if it's within "memory_limit").
Try this.

<?php

ini_set("memory_limit", "512M"); // <-- must be changed if you try 1G.
$length = 100000; // <-- 99999 is OK / 100000 is NG

$str = "";
for ($i=0; $i<$length; $i++):
    $str .= "1"; // <-- same result if it is a multibyte character.
endfor;

if (mb_ereg('.*', $str)):
    echo '<br><span style="background-color:lightgreen">OK!</span><br>memory_limit = '.ini_get("memory_limit").'<br>$length = '.$length;
else:
    echo '<br><span style="background-color:orange">NG!</span><br>memory_limit = '.ini_get("memory_limit").'<br>$length = '.$length;
endif;

?>

down

Anonymous ¶

3 years ago

If adding ".*" at the end of the pattern returns "false" 
whereas only one "." returns "true",

Suspect the string is too long for the pattern matching.

In this case, using preg_match() returns "true" when putting ".*" 
, but adding more "$" or "\z" returns "false" as expected.

down

Anonymous ¶

4 years ago

mb_ereg() with a named-subpattern
never catches non-named-subpattern.
(Oniguruma's restriction)

<?php

$str = 'abcdefg';
$patternA = '\A(abcd)(.*)\z';        // both caught [1]abcd [2]efg
$patternB = '\A(abcd)(?<rest>.*)\z'; // non-named 'abcd' never caught

mb_ereg($patternA, $str, $match);
echo '<pre>'.print_r($match, true).'</pre>';

mb_ereg($patternB, $str, $match);
echo '<pre>'.print_r($match, true).'</pre>';
?>

Array
(
    [0] => abcdefg
    [1] => abcd
    [2] => efg
)

Array
(
    [0] => abcdefg
    [1] => efg
    [rest] => efg
)

down

Anonymous ¶

4 years ago

<?php

# What mb_ereg() returns & changes $_3rd_argument into
# (Just run this script)

function dump2str($var) {
    ob_start();
    var_dump($var);
    $output = ob_get_contents();
    ob_end_clean();
    return $output;
}

# (PHP7)empty pattern returns bool(false) with Warning
# (PHP8)empty pattern throws ValueError
    $emp_ptn = '';
try{
    $emp_ptn.=  dump2str(mb_ereg('', 'abcde'));
}catch(Exception | Error $e){
    $emp_ptn.=  get_class($e).'<br>';
    $emp_ptn.=  $e->getMessage();
    $emp_ptn.=  '<pre>'.$e->getTraceAsString().'</pre>';
}

echo
'PHP '.phpversion().'<br><br>'.

'# match<br>'.
dump2str(mb_ereg("bcd", "abcde")).
' : mb_ereg("bcd", "abcde")<br><br>'.

'# match with 3rd argument<br>'.
dump2str(mb_ereg("bcd", "abcde", $_3rd)).
' : mb_ereg("bcd", "abcde", $_3rd)    // '.dump2str($_3rd).'<br><br>'.

'# match (0 byte)<br>'.
dump2str(mb_ereg("^", "abcde")).
' : mb_ereg("^", "abcde")<br><br>'.

'# match (0 byte) with 3rd argument<br>'.
dump2str(mb_ereg("^", "abcde", $_3rd)).
' : mb_ereg("^", "abcde", $_3rd)    // '.dump2str($_3rd).'<br><br>'.

'# unmatch<br>'.
dump2str(mb_ereg("f", "abcde")).
' : mb_ereg("f", "abcde")<br><br>'.

'# unmatch with 3rd argument<br>'.
dump2str(mb_ereg("f", "abcde", $_3rd)).
' : mb_ereg("f", "abcde", $_3rd)    // '.dump2str($_3rd).'<br><br>'.

'# empty pattern<br>'.
$emp_ptn.
' : mb_ereg("", "abcde")<br><br>'.

'# empty pattern with 3rd argument<br>'.
$emp_ptn.
' : mb_ereg("", "abcde", $_3rd)    // '.dump2str($_3rd).'<br><br>';

?>

down

lastuser at example dot com ¶

7 years ago

I hope this information is shown somewhere on php.net.

According to "https://github.com/php/php-src/tree/PHP-5.6/ext/mbstring/oniguruma",
the bundled Oniguruma regex library version seems ...
 4.7.1 between PHP 5.3 - 5.4.45,
 5.9.2 between PHP 5.5 - 7.1.16,
 6.3.0 since PHP 7.2 - .

down

mb_ereg() seems unable to Use "named sub ¶

10 years ago

mb_ereg() seems unable to Use "named subpattern".
preg_match() seems a substitute only in UTF-8 encoding.

<?php

$text = 'multi_byte_string';
$pattern = '.*(?<name>string).*';        // "?P" causes "mbregex compile err" in PHP 5.3.5

if(mb_ereg($pattern, $text, $matches)){
    echo '<pre>'.print_r($matches, true).'</pre>';
}else{
    echo 'no match';
}

?>

This code ignores "?<name>" in $pattern and displays below.

Array
(
    [0] => multi_byte_string
    [1] => string
)

$pattern = '/.*(?<name>string).*/u';
if(preg_match($pattern, $text, $matches)){

instead of lines 2 & 3
displays below (in UTF-8 encoding).

Array
(
    [0] => multi_byte_string
    [name] => string
    [1] => string
)

down

-1

Anonymous ¶

6 years ago

<?php

// in PHP_VERSION 7.1

// WITHOUT $regs (3rd argument)
$int = mb_ereg('abcde', '_abcde_'); // [5 bytes match]
var_dump($int);                     // int(1)

$int = mb_ereg('ab', '_ab_');       // [2 bytes match]
var_dump($int);                     // int(1)

$int = mb_ereg('^', '_ab_');        // [0 bytes match]
var_dump($int);                     // int(1)

$int = mb_ereg('ab', '__');         // [not match]
var_dump($int);                     // bool(false)

$int = mb_ereg('', '_ab_');         // [error : empty pattern]
                                    // Warning: mb_ereg(): empty pattern in ...
var_dump($int);                     // bool(false)

$int = mb_ereg('ab');               // [error : fewer arguments]
                                    // Warning: mb_ereg() expects at least 2 parameters, 1 given in ...
var_dump($int);                     // bool(false)

                    // Without 3rd argument, mb_ereg() returns either int(1) or bool(false).

// WITH $regs (3rd argument)
$int = mb_ereg('abcde', '_abcde_', $regs);// [5 bytes match]
var_dump($int);                           // int(5)
var_dump($regs);                          // array(1) { [0]=> string(5) "abcde" }

$int = mb_ereg('ab', '_ab_', $regs);      // [2 bytes match]
var_dump($int);                           // int(2)
var_dump($regs);                          // array(1) { [0]=> string(2) "ab" }

$int = mb_ereg('^', '_ab_', $regs);       // [0 bytes match]
var_dump($int);                           // int(1)
var_dump($regs);                          // array(1) { [0]=> bool(false) }

$int = mb_ereg('ab', '__', $regs);        // [not match]
var_dump($int);                           // bool(false)
var_dump($regs);                          // array(0) { }

$int = mb_ereg('', '_ab_', $regs);        // [error : empty pattern]
                                          // Warning: mb_ereg(): empty pattern in ...
var_dump($int);                           // bool(false)
var_dump($regs);                          // array(0) { }

$int = mb_ereg('ab');                     // [error : fewer arguments]
                                          // Warning: mb_ereg() expects at least 2 parameters, 1 given in ...
var_dump($int);                           // bool(false)
var_dump($regs);                          // array(0) { }

                    // With 3rd argument, mb_ereg() returns either int(how many bytes matched) or bool(false)
                    // and 3rd argument is a bit complicated.

?>

down

-2

Riikka K ¶

11 years ago

While hardly mentioned anywhere, it may be useful to note that mb_ereg uses Oniguruma library internally. The syntax for the default mode (ruby) is described here:

http://www.geocities.jp/kosako3/oniguruma/doc/RE.txt

down

-2

Jon ¶

16 years ago

Hebrew regex tested on PHP 5, Ubuntu 8.04.

Seems to work fine without the mb_regex_encoding lines (commented out).

Didn't seem to work with \uxxxx (also commented out).



<?php

echo "Line ";

//mb_regex_encoding("ISO-8859-8");

//if(mb_ereg(".*([\u05d0-\u05ea]).*", $this->current_line))

if(mb_ereg(".*([א-ת]).*", $this->current_line))

{

    echo "has";

}

else

{

    echo "doesn't have";

}

echo " Hebrew characters.<br>";    

//mb_regex_encoding("UTF-8");

?>

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