How to build the keys of a multidimensional array in PHP from the values of another array?

Question

I have a problem that I'm struggling to solve.

I have two arrays.

One is

$array1 = array('eligibility', 'eligibility_section');

But it could be an unknown length.

The other will hopefully contain the values above in its keys. Eg it might look like this.

$array2 = array('eligibility' => array('eligibility_section' => 'some_val));

I need a way to check if the values in array1 exist as keys in array2, and they must exist in the same order. E.g. from the example above if the order of array1 was:

array('eligibility_section', 'eligibility');

The method would return false.

Sorry if its a stupid question but I'm very tired.

Avag Sargsyan · Accepted Answer · 2017-12-16 11:34:28Z

4

Hopefully the following code will solve your problem.

$array1 = array('eligibility', 'eligibility_section', 'some_key');
$array2 = array('eligibility' => array('eligibility_section' => array('some_key' => 'some_val' ) ) );

function is_keys_exist( $array1, $array_to_compare ) {
    $i = 0;
    foreach( $array_to_compare as $key1 => $val1 ) {
        if( $key1 !== $array1[$i] ) {
            return false;
        }
        ++$i;
        if( is_array( $val1 ) ) {
            is_keys_exist( $array1, $val1 );
        }
    }
    return true;
}

var_dump( is_keys_exist( $array1, $array2 ) );

edited Dec 16, 2017 at 11:34

answered Oct 12, 2016 at 8:13

Avag Sargsyan

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deceze · Accepted Answer · 2016-10-12 08:28:50Z

1

This can be done with a simple array reduction:

$array1 = array('eligibility', 'eligibility_section');
$array2 = array('eligibility' => array('eligibility_section' => 'some_val'));

$result = array_reduce($array1, function ($subject, $key) {
    return is_array($subject) && array_key_exists($key, $subject) ? $subject[$key] : false;
}, $array2);

echo $result ? 'true' : 'false';

With the PHP 7 null coalescing operator this can be shortened to this, though beware that your values must not be null for this to return the correct result:

array_reduce($array1, function ($s, $k) { return $s[$k] ?? false; }, $array2)

edited Oct 12, 2016 at 8:28

answered Oct 12, 2016 at 8:23

deceze♦

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