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
?>
in_array
(PHP 4, PHP 5, PHP 7, PHP 8)
in_array — Comprueba si un valor existe en un array
Descripción
Busca la aguja (needle) en el pajar (haystack) usando una
comparación flexible a menos que esté establecido strict.
Parámetros
-
needle -
El valor a buscar.
Nota:
Si
needlees un string, la comparación se realiza considerando las mayúsculas/minúsculas. -
haystack -
El array.
-
strict -
Si el tercer parámetro
strictestá establecido atrue, la función in_array() también comprobará los tipos deneedleenhaystack.
Valores devueltos
Devuelve true si needle se encuentra en el array,
false de lo contrario.
Ejemplos
Ejemplo #1 Ejemplo de in_array()
<?php
$os = array("Mac", "NT", "Irix", "Linux");
if (in_array("Irix", $os)) {
echo "Existe Irix";
}
if (in_array("mac", $os)) {
echo "Existe mac";
}
?>La segunda condición falla porque in_array() considera las mayúsculas-minúsculas, así que el programa anterior mostrará:
Existe Irix
Ejemplo #2 Ejemplo de in_array() en modo estricto
<?php
$a = array('1.10', 12.4, 1.13);
if (in_array('12.4', $a, true)) {
echo "Se encontró '12.4' con comprobación estricta\n";
}
if (in_array(1.13, $a, true)) {
echo "Se encontró 1.13 con comprobación estricta\n";
}
?>El resultado del ejemplo sería:
Se encontró 1.13 con comprobación estricta
Ejemplo #3 in_array() con un array como aguja
<?php
$a = array(array('p', 'h'), array('p', 'r'), 'o');
if (in_array(array('p', 'h'), $a)) {
echo "Se encontró 'ph'\n";
}
if (in_array(array('f', 'i'), $a)) {
echo "Se encontró 'fi'\n";
}
if (in_array('o', $a)) {
echo "Se encontró 'o'\n";
}
?>El resultado del ejemplo sería:
Se encontró 'ph' Se encontró 'o'
Ver también
- array_search() - Busca un valor determinado en un array y devuelve la primera clave correspondiente en caso de éxito
- isset() - Determina si una variable está definida y no es null
- array_key_exists() - Verifica si el índice o clave dada existe en el array
add a note
User Contributed Notes 8 notes
beingmrkenny at gmail dot com ¶
13 years ago
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;
}
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.
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.
leonhard dot radonic+phpnet at gmail dot com ¶
1 year 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.
thomas dot sahlin at gmail dot com ¶
15 years ago
If you're creating an array yourself and then using in_array to search it, consider setting the keys of the array and using isset instead since it's much faster.
<?php
$slow = array('apple', 'banana', 'orange');
if (in_array('banana', $slow))
print('Found it!');
$fast = array('apple' => 'apple', 'banana' => 'banana', 'orange' => 'orange');
if (isset($fast['banana']))
print('Found it!');
?>
