PHP的开关内的情况下返回正常工作，但开关不工作后返回

Question

Can anyone help me with the following function, why return inside switch case is working (return correct converted price/quantity):

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, '.', '')];
    }
}

But this one is not? (return only case 136 converted price/quantity) ( return after switch is not working) How can I improve from the above one, I want to use less code to do the above function, thanks!

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

Add the break; statement at the end of each case . Otherwise the code of the next case s of the switch statement will be executed too. Your return statement uses variables that are defined in the switch statement. If somehow $unit_id is not in the list of case s, the return will fail in error. To prevent the return from failing, you could add this at the bottom of the case list:

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

Or you could throw an Exception.

Answer 2

Return退出该函数，因此在您的情况下充当中断，这就是为什么它在第一种情况下起作用的原因。