Wondering why your preg_replace fails, even if you have used preg_quote?
Try adding the delimiter / - preg_quote($string, '/');
preg_quote
(PHP 4, PHP 5, PHP 7, PHP 8)
preg_quote — Adiciona escape em caracteres da expressão regular
Descrição
preg_quote
( string
$str
, string $delimiter = ?
) : string
preg_quote() pega str
e coloca uma barra invertida antes de cada caractere que é parte da
sintaxe da expressão regular. Isto é útil se você tem uma
string em run-time que você precisa combinar em algum texto e a
string pode conter caracteres especiais de regex.
Os caracteres especiais da expressão regular são
. \ + * ? [ ^ ] $ ( ) { } = ! < > | :
Parâmetros
-
str -
A string de entrada.
-
delimiter -
Se o opcional
delimiteré especificado, ele também terá escape antecedendo. Isto é útil para adicionar escape em delimitadores que é requerido pelas funções PCRE. A / é o delimitador mais comumente usado.
Valor Retornado
Retorna a string modificada.
Exemplos
Exemplo #1 Exemplo da preg_quote()
<?php
$keywords = '$40 for a g3/400';
$keywords = preg_quote($keywords, '/');
echo $keywords; // returns \$40 for a g3\/400
?>
Exemplo #2 Deixando em itálico uma palavra de um texto
<?php
// In this example, preg_quote($word) is used to keep the
// asterisks from having special meaning to the regular
// expression.
$textbody = "This book is *very* difficult to find.";
$word = "*very*";
$textbody = preg_replace ("/" . preg_quote($word) . "/",
"<i>" . $word . "</i>",
$textbody);
?>
Notas
Nota: Esta função é binary-safe.
add a note
User Contributed Notes 7 notes
Anonymous ¶
16 years ago
zooly ¶
14 years ago
To escape characters with special meaning, like: .-[]() and so on, use \Q and \E.
For example:
<?php echo ( preg_match('/^'.( $myvar = 'te.t' ).'$/i', 'test') ? 'match' : 'nomatch' ); ?>
Will result in: match
But:
<?php echo ( preg_match('/^\Q'.( $myvar = 'te.t' ).'\E$/i', 'test') ? 'match' : 'nomatch' ); ?>
Will result in: nomatch
rawr at t-regx dot com ¶
3 years ago
To have a higher level control of what your pattern looks like, try T-Regx:
Pattern::inject('This is (my|our) pattern: @', [$_GET['name']]);
Anonymous ¶
3 years ago
I discovered that, in addition to escaping the special regular expression characters, preg_quote() encodes the NUL byte to its octal representation:
<?php
var_dump(preg_quote("\0"));
?>
Output:
string(4) "\000"
ed at happysoftware dot com ¶
4 years ago
It should be noted that the forward slash is not escaped. Since many regexes are surrounded by forward slashes, if you have one in your regex as text you must escape it yourself otherwise it'll terminat the regex.
rwillmann at crooce dot com ¶
6 years ago
List of specials is incomplete:
--- sample code ---
$specials = '.\+*?[^]$(){}=!<>|:-';
for ($i = 0; $i <= 255; $i++) {
if (chr($i) !== preg_quote(chr($i))) {
printf("Character 0x%02x quoted%s\n",
$i,
(strpos($specials, chr($i)) === FALSE) ? ' (+)' : '');
} /* if */
} /* for */
--- sample code ---
--- output ---
Character 0x00 quoted (+)
Character 0x21 quoted
Character 0x24 quoted
Character 0x28 quoted
Character 0x29 quoted
Character 0x2a quoted
Character 0x2b quoted
Character 0x2d quoted
Character 0x2e quoted
Character 0x3a quoted
Character 0x3c quoted
Character 0x3d quoted
Character 0x3e quoted
Character 0x3f quoted
Character 0x5b quoted
Character 0x5c quoted
Character 0x5d quoted
Character 0x5e quoted
Character 0x7b quoted
Character 0x7c quoted
Character 0x7d quoted
--- output ---
noreply at t-regx dot com ¶
4 years ago
If you find yourself using too much of preg_quote(), it's a good sign you might want to use Prepared Patterns from T-Regx library: https://t-regx.com/docs/handling-user-input
