in_array

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

in_array — Controlla se un valore è presente in un array

Descrizione

in_array(mixed $ago, array $pagliaio, bool $strict = ?): bool

Cerca in pagliaio per trovare ago e restituisce true se viene trovato nell'array, false altrimenti.

Se il terzo parametro strict è true la funzione in_array() controllerà anche il tipo di ago nell'array haystack.

Nota:
Se ago è una stringa, il confronto è effettuato tenendo conto delle maiuscole/minuscole.

Nota:
Nelle versioni di PHP precedenti la 4.2.0. ago non poteva essere un array.

Example #1 esempio di in_array()

<?
$os = array("Mac", "NT", "Irix", "Linux");
if (in_array("Irix", $os)) {
    echo "Trovato Irix";
}
if (in_array("mac", $os)) {
    echo "Trovato mac";
}
?>

La seconda condizione fallisce perché in_array() tiene conto di maiuscole e minuscole, quindi il programma mostrerà:

Trovato Irix

Example #2 esempio di in_array() con strict

<?php
$a = array('1.10', 12.4, 1.13);

if (in_array('12.4', $a, true)) {
    echo "'12.4' trovato con controllo strict\n"
}

if (in_array(1.13, $a, true)) {
    echo "1.13 trovato con controllo strict\n"
}
?>

Questo mostrerà:

1.13 trovato con controllo strict

Example #3 in_array() con un array come ago

<?php
$a = array(array('p', 'h'), array('p', 'r'), 'o');

if (in_array(array('p', 'h'), $a)) {
    echo "'ph' trovato\n";
}

if (in_array(array('f', 'i'), $a)) {
    echo "'fi' non trovato\n";
}

if (in_array('o', $a)) {
    echo "'o' trovato\n";
}
?>

Questo ritornerà:

  'ph' trovato
  'o' trovato

Vedere anche array_search(), array_key_exists() e isset().

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User Contributed Notes 5 notes

down

411

beingmrkenny at gmail dot com ¶

13 years ago

Loose checking returns some crazy, counter-intuitive results when used with certain arrays. It is completely correct behaviour, due to PHP's leniency on variable types, but in "real-life" is almost useless.

The solution is to use the strict checking option.

<?php

// Example array

$array = array(
    'egg' => true,
    'cheese' => false,
    'hair' => 765,
    'goblins' => null,
    'ogres' => 'no ogres allowed in this array'
);

// Loose checking -- return values are in comments

// First three make sense, last four do not

in_array(null, $array); // true
in_array(false, $array); // true
in_array(765, $array); // true
in_array(763, $array); // true
in_array('egg', $array); // true
in_array('hhh', $array); // true
in_array(array(), $array); // true

// Strict checking

in_array(null, $array, true); // true
in_array(false, $array, true); // true
in_array(765, $array, true); // true
in_array(763, $array, true); // false
in_array('egg', $array, true); // false
in_array('hhh', $array, true); // false
in_array(array(), $array, true); // false

?>

down

Julian Sawicki ¶

1 year ago

Here is a recursive in_array function: 

<?php

$myNumbers = [
    [1,2,3,4,5],
    [6,7,8,9,10],
];

$array = [
    'numbers' => $myNumbers
];

// Let's try to find number 7 within $array
$hasNumber = in_array(7, $array, true); // bool(false)
$hasNumber = in_array_recursive(7, $array, true); // bool(true)

function in_array_recursive(mixed $needle, array $haystack, bool $strict): bool
{
    foreach ($haystack as $element) {
        if ($element === $needle) {
            return true;
        }

        $isFound = false;
        if (is_array($element)) {
            $isFound = in_array_recursive($needle, $element, $strict);
        }
        
        if ($isFound === true) {
            return true;
        }
    }

    return false;
}

down

rhill at xenu-directory dot net ¶

15 years ago

I found out that in_array will *not* find an associative array within a haystack of associative arrays in strict mode if the keys were not generated in the *same order*:

<?php

$needle = array(
    'fruit'=>'banana', 'vegetable'=>'carrot'
    );

$haystack = array(
    array('vegetable'=>'carrot', 'fruit'=>'banana'),
    array('fruit'=>'apple', 'vegetable'=>'celery')
    );

echo in_array($needle, $haystack, true) ? 'true' : 'false';
// Output is 'false'

echo in_array($needle, $haystack) ? 'true' : 'false';
// Output is 'true'

?>

I had wrongly assumed the order of the items in an associative array were irrelevant, regardless of whether 'strict' is TRUE or FALSE: The order is irrelevant *only* if not in strict mode.

down

leonhard dot radonic+phpnet at gmail dot com ¶

2 years ago

I got an unexpected behavior working with in_array. I'm using following code:

<?php
// ...
$someId = getSomeId(); // it gets generated/fetched by another service, so I don't know what value it will have. P.S.: it's an integer

// The actual data in my edge-case scenario:
// $someId = 0;
// $anyArray = ['dataOne', 'dataTwo'];
if (in_array($someId, $anyArray)) {
    // do some work
}
// ...
?>

With PHP7.4, in_array returns boolean true.
With PHP8.1, in_array returns boolean false.

It took me quite some time to find out what's going on.

down

-4

Armands Rieksti ¶

1 year ago

I'd like to point out that, if you're using Enum data structures and want to compare whether an array of strings has a certain string Enum in it, you need to cast it to a string.

From what I've tested, the function works correctly:
if the array is filled with strings and you're searching for a string;
if the array is filled with Enums and you're searching for an Enum.

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