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    preg_grep

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

    preg_grep — Retorna as entradas do array que combinaram com o padrão

    Descrição

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

    Retorna o array consistindo dos elementos do array de input que combinaram com o dado pattern.

    Parâmetros

    pattern

    A string do padrão.

    input

    O array de entrada.

    flags

    Se usado PREG_GREP_INVERT, esta função retorna os elementos do array de entrada que não casam com o dado pattern.

    Valor Retornado

    Retorna um array indexado usando a chave do array de input.

    Changelog

    Versão Descrição
    4.2.0 O parâmetro flags foi adicionado.
    4.0.4

    Antes desta versão, o array retornado era indexado diferente das chaves do array de input.

    Se você quer reproduzir o antigo comportamento, use array_values() no array retornado para reindexar os valores.

    Exemplos

    Exemplo #1 Exemplo da preg_grep()

    <?php
    // retorna todos os elementos do array
    // contendo números de ponto flutuante
    $fl_array = preg_grep("/^(\d+)?\.\d+$/", $array);
    ?>

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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
    5 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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