php减去关联数组

Question

我有两个关联数组。我需要减去 ($price - $tax) 以获得 $total price：

 $price['lunch'] = array("food" => 10, "beer"=> 6, "wine" => 9);
 $price['dinner'] = array("food" => 15, "beer"=> 10, "wine" => 10);

 $tax['lunch'] = array("food" => 2, "beer"=> 3, "wine" => 2);
 $tax['dinner'] = array("food" => 4, "beer"=> 6, "wine" => 4);

所需的结果数组：

 $result['lunch'] = (['food'] => 8, ['beer'] =>3, ['wine'] => 7 )
 $result['dinner'] = (['food'] => 11, ['beer'] =>4, ['wine'] => 6   )

我正在尝试以下函数和 array_map 无济于事：

function minus($a, $b) {
    return $a - $b;
 }

      foreach ($price as  $value)
        {
            $big = $value;
            foreach($tax as $v) {
                $small = $v;
        $e[] = array_map("minus",$big, $small);
        }       
        }

上面我得到四个数组（第一个和最后一个是正确的）所以它不正确。感谢您提供任何信息！

Answer 1

您可以使用键而不是数组映射进行比较。使用双 foreach，您可以执行任意数量的膳食和食物类型：

foreach(array_keys($price) as $meal)
{
    foreach(array_keys($price[$meal]) as $type)
    {
        $e[$meal][$type] = $price[$meal][$type] - $tax[$meal][$type];
    }
}

请注意，此代码不会查找餐点或食物类型中丢失的项目...