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 — Escapar caracteres en una expresión regular
Descripción
preg_quote() toma string
y pone una barra invertida delante de cada carácter que es parte de
la sintaxis de la expresión regular. Esto es útil si tiene una
cadena en tiempo de ejecución que necesite comparar con algún texto, y la
cadena pueda contener caracteres de expresiones regulares especiales.
Los caracteres de expresiones regulares especiales son:
. \ + * ? [ ^ ] $ ( ) { } = ! < > | : -
Observe que / no es un carácter especial de expresión regular.
Nota:
Observe que preg_quote() no está pensada para que sea apliaca a los strings de preg_replace() etc.
Parámetros
-
string -
La cadena de entrada.
-
delimiter -
Si se especifica el parámetro opcional
delimiter, éste también será escapado. Esto es útil para escapar el delimitador que es necesario para las funciones PCRE. El delimitador/es el que se usa comúnmente.
Valores devueltos
Devuelve el string entrecomillado (escapado).
Historial de cambios
| Versión | Descripción |
|---|---|
| 5.3.0 |
El carácter - ahora es escapado
|
Ejemplos
Ejemplo #1 Ejemplo de preg_quote()
<?php
$claves = '$40 por un a g3/400';
$claves = preg_quote($claves, '/');
echo $claves; // devuelve \$40 por un g3\/400
?>
Ejemplo #2 Poner en cursiva una palabra dentro de un texto
<?php
// En este ejemplo, preg_quote($palabra) se usa para que los
// asteriscos sigan teniendo un significado especial en la
// expresión regular.
$texto = "Este libro es *muy* difícil de encontrar.";
$palabra = "*muy*";
$texto = preg_replace ("/" . preg_quote($palabra, '/') . "/",
"<i>" . $palabra . "</i>",
$texto);
?>Notas
Nota: Esta función es segura binariamente.
add a note
User Contributed Notes 7 notes
Anonymous ¶
16 years ago
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"
zooly ¶
15 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
ed at happysoftware dot com ¶
5 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 ¶
7 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($i)) === FALSE) ? ' (+)' : '');
} /* if */
} /* for */
--- sample code ---
--- output ---
Character 0x00 quoted (+)
Character 0x21 quoted
Character 0x24 quoted
Character 0x28 quoted
Character 0x29 quoted
Character 0x2a quoted
Character 0x2b quoted
Character 0x2d quoted
Character 0x2e quoted
Character 0x3a quoted
Character 0x3c quoted
Character 0x3d quoted
Character 0x3e quoted
Character 0x3f quoted
Character 0x5b quoted
Character 0x5c quoted
Character 0x5d quoted
Character 0x5e quoted
Character 0x7b quoted
Character 0x7c quoted
Character 0x7d quoted
--- output ---
rawr at t-regx dot com ¶
3 years ago
To have a higher level control of what your pattern looks like, try T-Regx:
Pattern::inject('This is (my|our) pattern: @', [$_GET['name']]);
noreply at t-regx dot com ¶
5 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
