A shorter way to run a match on the array's keys rather than the values:<?phpfunction preg_grep_keys($pattern, $input, $flags = 0) { return array_intersect_key($input, array_flip(preg_grep($pattern, array_keys($input), $flags)));}?>
(PHP 4, PHP 5, PHP 7, PHP 8)
preg_grep — Retourne un tableau avec les résultats de la recherche
preg_grep() retourne un tableau qui contient
les éléments de array
qui satisfont le masque pattern.
patternLe motif à chercher, sous la forme d'une chaîne de caractères.
arrayLe tableau d'entrée.
flags
Si cette option vaut PREG_GREP_INVERT,
cette fonction retourne les éléments du tableau
input qui ne correspondent
pas au motif
pattern.
Retourne un tableau indexé, en utilisant les clés du
tableau array d'entrée, ou false si une erreur survient.
Si le masque regex passé ne compile pas à une regex valide, une E_WARNING est émise.
Exemple #1 Exemple avec preg_grep()
<?php
$array = [ "4", M_PI, "2.74", 42 ];
// retourne tous les éléments du tableau contenant des nombres à virgule flottante
$fl_array = preg_grep("/^(\d+)?\.\d+$/", $array);
var_dump($fl_array);
?>
A shorter way to run a match on the array's keys rather than the values:<?phpfunction preg_grep_keys($pattern, $input, $flags = 0) { return array_intersect_key($input, array_flip(preg_grep($pattern, array_keys($input), $flags)));}?>Run a match on the array's keys rather than the values:<?phpfunction preg_grep_keys( $pattern, $input, $flags = 0 ){ $keys = preg_grep( $pattern, array_keys( $input ), $flags ); $vals = array(); foreach ( $keys as $key ) { $vals[$key] = $input[$key]; } return $vals;}?>This may be obvious to most experienced developers,but just in case its not,when using preg_grep to check for whitelisted items ,one must be very careful to explicitly define the regex boundaries or it will fail<?php$whitelist = ["home","dashboard","profile","group"];$possibleUserInputs = ["homd","hom","ashboard","settings","group"];foreach($possibleUserInputs as $input){ if(preg_grep("/$input/i",$whitelist) { echo $input." whitelisted"; }else{ echo $input." flawed"; }}?>This results in:homd flawedhom whitelistedashboard whitelistedsettings flawedgroup whitelistedI think this is because if boundaries are not explicitly defined,preg_grep looks for any instance of the substring in the whole array and returns true if found.This is not what we want,so boundaries must be defined.<?phpforeach($possibleUserInputs as $input){ if(preg_grep("/^$input$/i",$whitelist) { echo $input." whitelisted"; }else{ echo $input." flawed"; }}?>this results in:homd flawedhom flawedashboard flawedsettings flawedgroup whitelistedin_array() will also give the latter results but will require few tweaks if say,the search is to be case insensitive,which is always the case 70% of the time