php在交换机内部的返回是工作的，但是在开关不工作后返回

Question

谁能帮我完成以下功能，为什么return在开关箱内工作(返回正确的转换价格/数量)：

function calcPriceAndQuantityFromLBS($price, $quantity, $unit_id, $lbs_in_a_bu, $lbs_in_w_bu) {
    switch ($unit_id) {
        case 8: // A Bushel
            $outQ = $quantity / $lbs_in_a_bu;
            $outP = $price * $lbs_in_a_bu;
            return ['quantity' => number_format($outQ, 3, '.', ''), 'price' => number_format($outP, 8, '.', '')];
        case 10: // Pounds
            $outQ = $quantity;
            $outP = $price;
            return ['quantity' => number_format($outQ, 3, '.', ''), 'price' => number_format($outP, 8, '.', '')];
        case 11: // CWT
            $outQ = $quantity / LBS_IN_CWT;
            $outP = $price * LBS_IN_CWT;
            return ['quantity' => number_format($outQ, 3, '.', ''), 'price' => number_format($outP, 8, '.', '')];
        case 12: // Metric Tonne
            $outQ = $quantity / LBS_IN_TON;
            $outP = $price * LBS_IN_TON;
            return ['quantity' => number_format($outQ, 3, '.', ''), 'price' => number_format($outP, 8, '.', '')];
        case 136: // W Bushel
            $outQ = $quantity / $lbs_in_w_bu;
            $outP = $price * $lbs_in_w_bu;
            return ['quantity' => number_format($outQ, 3, '.', ''), 'price' => number_format($outP, 8, '.', '')];
    }
}

但这个不是吗？(只返回case 136转换的价格/数量)(交换机不工作后的return)我如何从上面的一个改进，我想用较少的代码来做上述功能，谢谢！

function calcPriceAndQuantityFromLBS($price, $quantity, $unit_id, $lbs_in_a_bu, $lbs_in_w_bu) {
    switch ($unit_id) {
        case 8: // A Bushel
            $outQ = $quantity / $lbs_in_a_bu;
            $outP = $price * $lbs_in_a_bu;
        case 10: // Pounds
            $outQ = $quantity;
            $outP = $price;
        case 11: // CWT
            $outQ = $quantity / LBS_IN_CWT;
            $outP = $price * LBS_IN_CWT;
        case 12: // Metric Tonne
            $outQ = $quantity / LBS_IN_TON;
            $outP = $price * LBS_IN_TON;
        case 136: // W Bushel
            $outQ = $quantity / $lbs_in_w_bu;
            $outP = $price * $lbs_in_w_bu;
    }
    return ['quantity' => number_format($outQ, 3, '.', ''), 'price' => number_format($outP, 8, '.', '')];
}

Answer 1

在每个break;语句的末尾添加case语句。否则，switch语句的下一个switch的代码也将被执行。return语句使用在switch语句中定义的变量。如果$unit_id没有出现在case的列表中，那么return就会出错。为了防止return失败，可以在案例列表的底部添加以下内容：

default:  // $unit_id not found
  return ['quantity' => '0.000', 'price' => '0.000'];  // whatever you like

或者你可以抛出一个例外。

Answer 2

返回退出函数，因此在您的情况下充当中断，这就是它在第一种情况下工作的原因。