PHP Multi Dimensional Array Search returning Keys

Question

I am trying to search an array of arrays and if the needle is found I want to return or at least know the keys for the match.

For example given:

['foo'] => 
     ['bar'] => 'blah'

Searching for 'blah' I need to know there is a match and the keys are 'foo' and 'bar'

I have managed to implement a search which returns boolean for a match:

function search_array($needle, $haystack) {
        if(in_array($needle, $haystack)) {
            return true;
        }
        foreach($haystack as $element) {
            var_dump($element);
            if(is_array($element) && $this->search_array($needle, $element))
               return true;
        }
        return false;
}

But I am struggling with how to know the keys. Is this even possible?

Sᴀᴍ Onᴇᴌᴀ · Accepted Answer · 2017-06-14 05:02:21Z

3

Yes it is possible. One solution is to:

In the base case utilize array_search() to get the key.

In the recursive case, when iterating over each element in the haystack (before recursing) use the $key => $value syntax of foreach. Then when the recursive call yields a value, check if the returned value is an array (by using is_array()) - if so, use array_unshift() to push the current key onto the returned array. Otherwise return an array with the key and the returned value.

function search_array($needle, $haystack) {
    if(in_array($needle, $haystack)) {
        return array_search($needle, $haystack);
    }
    foreach($haystack as $key => $element) {
        if(is_array($element) && search_array($needle, $element)) {
            $searchReturn = search_array($needle, $element);
            if (is_array($searchReturn)) {
                array_unshift($searchReturn, $key);
                return $searchReturn;
            }
            return [$key, $searchReturn];
        }
    }
    return false;
}

See it demonstrated in this playground example.

edited Jun 14, 2017 at 5:02

answered Jun 14, 2017 at 3:15

Sᴀᴍ Onᴇᴌᴀ

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1 Comment

Alan A Over a year ago

Thanks that worked albeit I had to modify the return at line 3 to in_array in my case.

Dimitris K · Accepted Answer · 2017-06-14 03:22:35Z

1

You can do it like this, since it's 2-dimensional array.

function search_array($needle, $haystack) {
    foreach($haystack as $key => $value) {
        if ($value == $needle) {
            return array($key);
        } else if (is_array($value)) {
            foreach ($value as $k => $v) {
                if ($v == $needle) {
                    return array($key, $k);
                }
            }
        }
    }
}

For an n-dimensional array you should use a recursive function...

answered Jun 14, 2017 at 3:22

Dimitris K

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1 Comment

Alan A Over a year ago

This is an interesting non-recursive solution, thnaks

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