当键未知时,如何找到关联数组的第一/第二个元素?

在PHP中,当有关联数组时,例如:

$groups['paragraph'] = 3
$groups['line'] = 3

当您不知道键的值时,访问数组的第一个或第二个元素的语法是什么

在C#LINQ语句中是否有类似的内容,您可以说:

$mostFrequentGroup = $groups->first()?

或

$mostFrequentGroup = $groups->getElementWithIndex(0)?

或者,我必须使用foreach语句并像在下面的代码示例中那样选择它们:

//should return "paragraph"
echo getMostFrequentlyOccurringItem(array('line', 'paragraph', 'paragraph'));

//should return "line"
echo getMostFrequentlyOccurringItem(array('wholeNumber', 'date', 'date', 'line', 'line', 'line'));

//should return null
echo getMostFrequentlyOccurringItem(array('wholeNumber', 'wholeNumber', 'paragraph', 'paragraph'));

//should return "wholeNumber"
echo getMostFrequentlyOccurringItem(array('wholeNumber', '', '', ''));

function getMostFrequentlyOccurringItem($items) {

    //catch invalid entry
    if($items == null) {
        return null;
    }
    if(count($items) == 0) {
        return null;
    }

    //sort
    $groups = array_count_values($items);
    arsort($groups);

    //if there was a tie, then return null
    if($groups[0] == $groups[1]) { //******** HOW TO DO THIS? ***********
        return null;
    }

    //get most frequent
    $mostFrequentGroup = '';
    foreach($groups as $group => $numberOfTimesOccurrred) {
        if(trim($group) != '') {
            $mostFrequentGroup = $group;
            break;
        }
    }
    return $mostFrequentGroup;
}