我想用PHP写一个脚本，它会帮我做一些数学运算。
它应该完成以下任务：
示例
假设你有一家果汁网店。你想
-
将几种果汁保存到数据库中（想想：橙汁、柠檬汁、苹果汁）。
-
您还想节省这些果汁的份量和价格（例如100毫升/2.50美元）。
-
你想混合/混合不同的果汁，得到毫升/美元的总量。
如果我们将其相加：
橙汁：100毫升/2.50美元|我要50毫升=1.25美元。
苹果汁：100毫升/1.50美元|我要10毫升=0.15美元。
混合果汁总量：60毫升=1.40美元
到目前为止还不错。我写了以下代码：
<?php
function devide() {
$portion = 100; //variable for ml
$price = 2.50; //variable for price
$portionNew = 50; //value for new portion put into total mix
if($portionNew > 0) {
echo ($price / 100 * $portionNew); //calculates price of new portion
}
}
echo "Total Juice" . (" = ");
echo devide() . (" USD") ;
?>
这个代码只计算你从一杯果汁中取出的那部分的价格。如果你从100毫升果汁中取出30毫升，它将与价格相呼应。
这些是我的问题：
我如何使这个脚本不仅反映新的价格，而且反映新的部分（
$portionNew）？关于我希望最终脚本做什么，函数是正确的开始吗？或者我应该考虑对象或数组吗？
我应该如何继续这个脚本，这样它就会添加多个（
$portionNews/ $price）来告诉我最终的价格和我的总果汁混合物的比例？
-
只需在
devide函数中添加类似echo 'Portion: '.$portionNew的内容。（我相信你可能想称之为divide？） -
您可以创建一个
Juice类，但我认为在这种情况下这太过分了。我可能会坚持使用一个数组来存储果汁及其价格，以及一个混合多种果汁的功能。 -
你可以创建一个混合果汁的功能。您可以指定一个变量，该变量包含当前价格和混合物中的部分、要添加的果汁的类型和数量，它将返回一个表示混合物中果汁的新价格和数量的值。
如果你想把果汁储存在一个阵列中，它可能看起来像这样：
// In this case, we have an array that maps the juice type to a price (in cents
// per 100 ml).
$juices = array(
'orange' => 250,
'apple' => 150
);
// If you decide you need to store more information about a juice, you can change
// this array to map a juice type to another associative array that contains the
// price and your additional information.
// Beware: if you use this, you have to change the mixJuices function to access
// a juice's "price" value:
// $pricePerLiter = $juices[$juiceType]['price'] * 10;
$juices = array(
'orange' => array(
'price' => 250,
'color' => 'orange'
),
'apple' => array(
'price' => 150,
'color' => 'yellow'
)
);
请注意，我将价格设置为美分，而不是美元。通过这样做，我避免了在计算价格时使用浮点和所有与之相关的问题（请参阅PHP文档中关于浮点精度的红色通知）
混合果汁的功能可能是这样的：
// The function needs to know what's currently in the mix, which is why it's
// taking the $currentMix as a parameter. Also, it needs to know about all the
// available juices, which is why it's taking the $juices as another parameter.
// A mix is represented by an associative array that contains the current amount
// of juice in the mix (identified by "portion") and the current price
// (identified by "price"). Note that you need to pass the $juices array I
// defined earlier, so it can access the different types of juices and their
// prices.
function mixJuices($currentMix, $juices, $juiceType, $juicePortion)
{
$pricePerLiter = $juices[$juiceType] * 10;
$price = $pricePerLiter * $juicePortion / 1000;
$currentMix['portion'] = $currentMix['portion'] + $juicePortion;
$currentMix['price'] = $currentMix['price'] + $price;
return $currentMix;
}
该函数也可以编写为使用全局$mix变量。如果您这样做了，就不需要将$currentMix传递给函数。然而，您也将失去同时创建多个混合的能力（因为对修改后的mixJuices函数的所有调用都将修改相同的全局混合）。
你可以像这样使用我上面定义的函数：
// At the beginning, there's no juice at all, so it doesn't cost anything (yet)
$mix = array('portion' => 0, 'price' => 0);
// Let's mix some juice in
$mix = mixJuices($mix, $juices, 'apple', 500);
$mix = mixJuices($mix, $juices, 'orange', 250);
// Print the amount of juice and the price
// The price is divided by 100 so we can display it in dollars instead of cents
echo sprintf('%d milliliters of this juice mix will cost %.2f USD.',
$mix['portion'], $mix['price'] / 100);
这种方法可以让你做各种有趣的事情。
假设你有两个顾客想要点果汁混合物。通过创建两个不同的$mix阵列，您可以轻松混合同一类型的多种果汁：
// Process customer 1's order
$mixCustomer1 = array('portion' => 0, 'price' => 0);
$mixCustomer1 = mixJuices($mixCustomer1, $juices, 'apple', 250);
$mixCustomer1 = mixJuices($mixCustomer1, $juices, 'orange', 250);
echo sprintf('%d milliliters of this juice mix will cost %.2f USD.',
$mixCustomer1['portion'], $mixCustomer1['price'] / 100);
// 500 milliliters of this juice mix will cost 10.00 USD.
// Process customer 2's order
$mixCustomer2 = array('portion' => 0, 'price' => 0);
$mixCustomer2 = mixJuices($mixCustomer2, $juices, 'apple', 150);
$mixCustomer2 = mixJuices($mixCustomer2, $juices, 'orange', 350);
echo sprintf('%d milliliters of this juice mix will cost %.2f USD.',
$mixCustomer2['portion'], $mixCustomer2['price'] / 100);
// 500 milliliters of this juice mix will cost 11.00 USD.
现在假设客户2有某种代金券，任何果汁都可以打八折：
// Apply the discount
$discountedJuices = array_map(function($price) { return (1 - 0.2) * $price; }, $juices);
// Process customer 2's order
$mixCustomer2 = array('portion' => 0, 'price' => 0);
$mixCustomer2 = mixJuices($mixCustomer2, $discountedJuices, 'apple', 150);
$mixCustomer2 = mixJuices($mixCustomer2, $discountedJuices, 'orange', 350);
echo sprintf('%d milliliters of this juice mix will cost %.2f USD.',
$mixCustomer2['portion'], $mixCustomer2['price'] / 100);
// 500 milliliters of this juice mix will cost 8.80 USD.