Question

Let’s take this array as an example:

$arr = array(
    'foo' => 'foo',
    'bar' => array(
        'baz' => 'baz',
        'candy' => 'candy',
        'vegetable' => array(
            'carrot' => 'carrot',
        )
    ),
    'vegetable' => array(
        'carrot' => 'carrot2',
    ),
    'fruits' => 'fruits',
);

Now how to do a general search to check if a value exists whether as a key or a value in the array and his sub-arrays.

Answer 1

I think we may use a double control

if(multi_array_key_exists($needle, $haystack)||deep_in_array($needle, $haystack))
{
    //Value exists
}

multi_array_key_exists function:

function multi_array_key_exists( $needle, $haystack ) { 

    foreach ( $haystack as $key => $value ) : 

        if ( $needle == $key ) 
            return true; 

        if ( is_array( $value ) ) : 
             if ( multi_array_key_exists( $needle, $value ) == true ) 
                return true; 
             else 
                 continue; 
        endif; 

    endforeach; 

    return false; 
}

Source: http://www.php.net/manual/en/function.array-key-exists.php#92355

deep_in_array function:

function deep_in_array($needle, $haystack) {
    if(in_array($needle, $haystack)) {
        return true;
    }
    foreach($haystack as $element) {
        if(is_array($element) && deep_in_array($needle, $element))
            return true;
    }
    return false;
}

Source: php Checking if value exists in array of array