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

Question

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!

Answer 1

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