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    preg_grep

    (PHP 4, PHP 5, PHP 7, PHP 8)

    preg_grep — Retourne un tableau avec les résultats de la recherche

    Description

    preg_grep(string $pattern, array $array, int $flags = 0): array|false

    preg_grep() retourne un tableau qui contient les éléments de array qui satisfont le masque pattern.

    Liste de paramètres

    pattern

    Le motif à chercher, sous la forme d'une chaîne de caractères.

    array

    Le 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.

    Valeurs de retour

    Retourne un tableau indexé, en utilisant les clés du tableau array d'entrée, ou false si une erreur survient.

    Erreurs / Exceptions

    Si le masque regex passé ne compile pas à une regex valide, une E_WARNING est émise.

    Exemples

    Exemple #1 Exemple avec preg_grep()

    <?php
    // Recherche les nombres à virgule flottante dans le tableau
    $fl_array = preg_grep("/^(\d+)?\.\d+$/", $array);
    ?>

    Voir aussi

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    User Contributed Notes 4 notes

    up
    76
    Daniel Klein
    11 years ago
    A shorter way to run a match on the array's keys rather than the values:

    <?php
    function preg_grep_keys($pattern, $input, $flags = 0) {
        return     array_intersect_key($input, array_flip(preg_grep($pattern, array_keys($input), $flags)));
    }
    ?>
    up
    32
    keithbluhm at gmail dot com
    14 years ago
    Run a match on the array's keys rather than the values:

    <?php

    function 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;
    }

    ?>
    up
    9
    amolocaleb at gmail dot com
    6 years ago
    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 flawed
    hom whitelisted
    ashboard whitelisted
    settings flawed
    group whitelisted

    I 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.

    <?php
    foreach($possibleUserInputs as  $input)
    {
         if(    preg_grep("/^$input$/i",$whitelist)
        {
             echo     $input." whitelisted";
        }else{
             echo     $input." flawed";
        }

    }
    ?>
    this results in:
    homd flawed
    hom flawed
    ashboard flawed
    settings flawed
    group whitelisted
    in_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
    up
    -27
    Timo Klemm
    7 years ago
    An even shorter way to run a match on the array's keys rather than the values:

    <?php
    function preg_grep_keys($pattern, $input, $flags = 0) {
        return     array_flip( preg_grep($pattern, array_flip($input), $flags ) );
    }
    ?>
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