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preg_last_error

(PHP 5 >= 5.2.0, PHP 7, PHP 8)

preg_last_errorВозвращает код ошибки выполнения последнего регулярного выражения PCRE

Описание

preg_last_error(): int

Возвращает код ошибки выполнения последнего регулярного выражения PCRE.

Пример #1 Пример использования preg_last_error()

<?php

preg_match
('/(?:\D+|<\d+>)*[!?]/', 'foobar foobar foobar');

if (
preg_last_error() == PREG_BACKTRACK_LIMIT_ERROR) {
echo
'Был исчерпан лимит обратных ссылок!';
}

?>

Результат выполнения приведённого примера:

Был исчерпан лимит обратных ссылок!

Список параметров

У этой функции нет параметров.

Возвращаемые значения

Возвращает одну из следующих констант (описанных на отдельной странице.):

Смотрите также

  • preg_last_error_msg() - Возвращает сообщение об ошибке последней запущенной функции PCRE

add a note

User Contributed Notes 10 notes

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4
nicoSWD
3 years ago
PHP 8 has a native function to retrieve the actual error message, so these helper functions are no longer necessary.

https://www.php.net/preg_last_error_msg

<?php

preg_match
('/(?:\D+|<\d+>)*[!?]/', 'foobar foobar foobar');

if (
preg_last_error() !== PREG_NO_ERROR) {
echo
preg_last_error_msg(); // Prints "Backtrack limit exhausted"
}

?>
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13
gk at anuary dot com
10 years ago
In PHP 5.5 and above, getting the error message is as simple as:

<?php
echo array_flip(get_defined_constants(true)['pcre'])[preg_last_error()];
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8
andre at koethur dot de
11 years ago
Here is a more advanced function to convert an error code to text:

<?php

function preg_errtxt($errcode)
{
static
$errtext;

if (!isset(
$errtxt))
{
$errtext = array();
$constants = get_defined_constants(true);
foreach (
$constants['pcre'] as $c => $n) if (preg_match('/_ERROR$/', $c)) $errtext[$n] = $c;
}

return
array_key_exists($errcode, $errtext)? $errtext[$errcode] : NULL;
}

?>
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4
Daniel Klein
4 years ago
Here is a correction to one of the previous "get error message" snippets. It filters out the non-error codes which stops "Warning: array_flip(): Can only flip STRING and INTEGER values!" from being emitted due to ["PCRE_JIT_SUPPORT"]=>bool(true):

<?php
echo array_flip(array_filter(get_defined_constants(true)['pcre'], function ($value) {
return
substr($value, -6) === '_ERROR';
},
ARRAY_FILTER_USE_KEY))[preg_last_error()];
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1
Anonymous
4 years ago
If you use T-Regx library, to get the last constant, you can use

<?php

echo preg_last_error_constant(); // 'PREG_BAD_UTF8_ERROR'
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2
johan at bluemoonit dot net
14 years ago
The above function pcre_error_deocde [sic] is not correct - not all of the used constants are errors constants. For example, when the error is actually PREG_BAD_UTF8_ERROR, the function outputs the text for PREG_SPLIT_OFFSET_CAPTURE.
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1
zerodahero at gmail dot com
4 years ago
In PHP 7.3+, and depending on the environment, there may be other constants that aren't ints which will cause errors with array_flip. I opted to go with a RegexException and a filter on gk's note.

<?php

class RegexException extends \Exception {

public
$errorCode;

public function
__construct(
int $errorCode,
string $additionalMessage = null
) {
$this->errorCode = $errorCode;

$errorMessage = $this->getErrorString($errorCode) ?? 'Unknown regex error';
$additionalMessage = $additionalMessage ? " $additionalMessage" : '';

parent::__construct("Regex error thrown: $errorMessage." . $additionalMessage);
}

/**
* Gets an error string (const name) for the PCRE error code
*
* @param int $errorCode
*
* @return string|null
*/
private function getErrorString(int $errorCode): ?string
{
$pcreConstants = get_defined_constants(true)['pcre'] ?? [];

/*
* NOTE: preg_last_error() returns an int, but there are constants
* in PHP 7.3+ that are strings, bools, or otherwise. We can pretty
* safely filter out the non-integers to fetch the appropriate
* error constant name.
*/
$pcreConstants = array_filter($pcreConstants, function ($code) {
return
is_int($code);
});

$errorStrings = array_flip($pcreConstants);

return
$errorStrings[$errorCode] ?? null;
}

Usage:

throw new
RegexException(preg_last_error());
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0
eu at ericruiz dot com dot br
7 years ago
Take it into account before use this function.

My php --version
PHP 5.6.29 (cli) (built: Dec 8 2016 09:19:46)
Copyright (c) 1997-2016 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2016 Zend Technologies

On Linux Fedora 23 4.8.13-100.fc23.x86_64 #1 SMP Fri Dec 9 14:51:40 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

<?php
// @see http://stackoverflow.com/questions/4440626/how-can-i-validate-regex

// returns true because there is no opening "(" for the closing ")"
var_dump(preg_match('~InvalidRegular)Expression~', null) === false);

// this SHOULD be something different from 0, but...
var_dump(preg_last_error());
?>
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0
andre at koethur dot de
11 years ago
Just an addition to my previous note: In unicode mode (with "u" modifier), PREG_BAD_UTF8_ERROR only reflects errors in the subject string. If the pattern itself contains invalid characters, preg_match() (or preg_match_all()) returns false but preg_last_error() returns 0 indicating PREG_NO_ERROR. Instead, php issues a warning: "preg_match(): Compilation failed: invalid UTF-8 string at offset 0"
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-1
Vladimir Valikaev
4 years ago
Getting error as text (small update):

<?php
echo array_flip(array_filter(get_defined_constants(true)['pcre'], function($v) { return is_integer($v); }))[preg_last_error()];
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