php - php 中 foreach 和循环语句的问题

Question

我有许多 $competitors (这是从 MySQL 检索的对象数组)(例如 9 个)，我有 $competitors[i]->minSingleCarefee 数据，即费用数据。我想计算此费用数据的平均值，但数据集可能不完整，即我没有所有 9 个竞争对手的费用数据。因此，我通过使用 if 语句并在费用数据可用时递增 $data_available 来跟踪这一点。

我的问题是，代码似乎有缺陷，因为它只返回第一个竞争对手的费用值......我不知道为什么!另外，当我回显 $data_available 时，它​​总是最终为 0。

//declaring variables
$mm_avg_fees = 0;
$data_available = 0;

//function to calculate average fees
function avg_fees($competitors, $mm_avg_fees, $data_available){

        foreach ($competitors as $competitor) {
            //impose condition to increment data_available
            //only if there is data in the minSingleCareFee column for the $competitor
            if ($competitor->minSingleCareFee != NULL) {
                $mm_avg_fees = $mm_avg_fees + $competitor->minSingleCareFee;
                $data_available = $data_available + 1; 
            } else {}
        }
    return $mm_avg_fees / $data_available;
}

echo echo 'The current average for single room fees in your micromarket is: ' . avg_fees($competitors, $mm_avg_fees, $data_available);

Answer 1

使用这个:

//declaring variables
$mm_avg_fees = 0;
$data_available = 0;

//function to calculate average fees
function avg_fees($competitors, $mm_avg_fees, $data_available){

        foreach ($competitors as $competitor) {
            //impose condition to increment data_available
            //only if there is data in the minSingleCareFee column for the $competitor
            if (!empty($competitor->minSingleCareFee)) {
                $mm_avg_fees = $mm_avg_fees + $competitor->minSingleCareFee;
                $data_available = $data_available + 1; 
            }
        }
    return $mm_avg_fees / $data_available;
}

echo 'The current average for single room fees in your micromarket is: ' . avg_fees($competitors, $mm_avg_fees, $data_available);