[Day 29] PHP array_map

假设目前有阵列

$fruits = [
    ['id'=>0,'fruit'=>'apple','sweetness'=>2,'price'=>20],
    ['id'=>1,'fruit'=>'banana','sweetness'=>4,'price'=>15],
    ['id'=>2,'fruit'=>'grape','sweetness'=>5,'price'=>80],
    ['id'=>3,'fruit'=>'orange','sweetness'=>1,'price'=>70],
];

array_map

用来更新阵列中的值，产生出新的阵列。

$nfruits = array_map(function($fruit){
    $fruit['price'] = $fruit['price'] *2;
    return $fruit;
},$fruits);
print_r($nfruits);

就能取得一个price翻倍的新阵列

另外，也能将function函式提到array_map外，也能得到相同的结果

function doublePrice($fruit)
{
    $fruit['price'] = $fruit['price'] *2;
    return $fruit;
}
$nfruits = array_map("doublePrice",$fruits);
print_r($nfruits);

也能利用array_map做到阵列之间的比较
array_map("function",阵列一,阵列二,...);

function doublePrice($fruit,$a)
{
    if($fruit['fruit'] == $a)
        return "same";
    return "different";
}
$array = array("apple","lemon","pineaple","orange");
$nfruits = array_map("doublePrice",$fruits,$array);
print_r($nfruits);