假设你实际上是指像这样的数组

array('key1' => null, 'key2' => null, 'key3' => null, 'key4' => null)

答案是简单地使用array_filter

if (!array_filter($array)) {
    // all values are empty (where "empty" means == false)
}

你的假设是不正确的。array('key1', 'key2', 'key3', 'key4')在0..3范围内有4个值和键。
array('key1', 'key2' => value2, 'key3', 'key4' => value4)的值为key1（键为0），键为key2，值为key3（键为1），键为key4。

如果需要检查所有值是否都是null

$allNull = true;
foreach( $array as $key => $val ) {
    if( is_null( $array[$key] ) ) {
        $allNull = false;
        break;
    }
}

// Do what you will with $allNull

$array = array('key1' => null, 'key2' => null, 'key3' => null, 'key4' => null);

答案是

$filterArray = array_filter($array);

if(count($filterArray) == 0){
    return false;
}else{
    return true;
}

$flag = 0;
foreach($array as $keys)
{
        if(!isempty($keys)) {
        $flag++;
        }
}

if(flag > 0)
{
    echo "Array not empty!";
}
else {
    echo "Array empty!";
}

应该可以

简单

count(array_filter($array)) != count($array)

如果多维

count(array_filter(array_values($array))) != count(array_values($array))