How to keep only specific array keys/values in array?

multidimensional-array, php

Solution

`array_intersect()` isn't recursive. The function assumes the array is just one level deep and expects all the array elements to be scalars. When it finds a non-scalar value, i.e. a sub-array, it throws a Notice.

This is vaguely mentioned in the documentation for `array_intersect()`:

Note: Two elements are considered equal if and only if: (string) $elem1 === (string) $elem2. In words: when the string representation is the same.

One solution I could think of is to use `array_filter()`:

$lookfor = array('html', 'slide');
$found   = array_filter($options, function($item) use ($lookfor) {
    return in_array($item, $lookfor);
});

Note: This still performs a looping and isn't any better than a simple `foreach`. In fact, it might be slower than a `foreach` if the array is large. I have no idea why you're trying to avoid loops — I personally think it'd be more cleaner if you just use a loop.

Demo

Another solution I could think of is to remove the sub-arrays before using `array_intersect()`:

<?php

$options = array(
    'index1' => 'html',
    'index2' => 'html',
    'index3' => 'slide',
    'index4' => 'tab',
    'index5' => array(123),
);

$lookfor = array('html', 'slide');
$scalars = array_filter($options,function ($item) { return !is_array($item); });
$found = array_intersect ($scalars, $lookfor);

print_r($found);

Demo

Problem

I have a multidimensional array that I am searching trough for specific values. If those values are found I need to extract the indexes with those values ( make new array ) and remove all others. array_intersect worked fine on php 5.3 , now on 5.4 it complains Notice: Array to string conversion. I found that array_intersect has an issue with multidimensional array on 5.4. https://bugs.php.net/bug.php?id=60198 This is $options array I am searching trough ``` Array ( [index1] => html [index2] => html [index3] => slide [index4] => tab [index5] => Array ( [0] => 123 ) ) ``` code that works on php 5.3.x ``` $lookfor = array('slide', 'tab'); $found = array_intersect($options, $lookfor); print_r($found); Array ( [index3] => slide [index4] => tab ) ``` but in 5.4.x this trows the error mentioned above. What would be another way to do this without a loop please. and without suppressing the error. Thank you!

Original source