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    preg_grep

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

    preg_grep — Devuelve entradas de matriz que coinciden con el patrón

    Descripción

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

    Devuelve la matriz consistente en los elementos de la matriz input que coinciden con pattern.

    Parámetros

    pattern

    El patrón de búsqueda, como cadena.

    input

    La matriz de entrada.

    flags

    Si se establece a PREG_GREP_INVERT, esta función devuelve los elementos de la matriz de entrada que no coinciden con pattern.

    Valores devueltos

    Devuelve una matriz indexada usando las claves de la matriz input.

    Ejemplos

    Ejemplo #1 Ejemplo de preg_grep()

    <?php
    // devuelve todos los elementos de la matriz
    // que contienen números de coma (punto) flotante
    $matriz_fl = preg_grep("/^(\d+)?\.\d+$/", $matriz);
    ?>

    Ver también

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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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