【array_map】对数组元素依次进行处理

array_map ( callable $callback , array $array1 [, array $... ] ) : array

<?php
$a = [
    ['id' => 1, 'name' => '千金'],
    ['id' => 2, 'name' => null],
    ['id' => 3, 'name' => '一刻'],
];

$res1 = [];
foreach ($a as $arr) {
    if (!$arr['name']) {
        $arr['name'] = '匿名';
    }
    $res1[] = $arr;
}

$res2 = array_map(function ($value) {
    if (!$value['name']) {
        $value['name'] = '匿名';
    }
    return $value;
}, $a);

var_dump($res1 == $res2);

/*
bool(true)
*/

<?php
$arr = ['stringkey' => 'value'];
var_dump(array_map(null,  $arr));

/*
array(1) {
  ["stringkey"]=>
  string(5) "value"
}
*/

$a = [1, 2, 3,];
$b = ['one', 'two', 'three', ];
$c = ['uno', 'dos', ];

$d = array_map(null, $a, $b, $c);
print_r($d);

/*
Array
(
    [0] => Array
        (
            [0] => 1
            [1] => one
            [2] => uno
        )

    [1] => Array
        (
            [0] => 2
            [1] => two
            [2] => dos
        )

    [2] => Array
        (
            [0] => 3
            [1] => three
            [2] =>
        )

)
*/

function triple($n)
{
    return $n * 3;
}

$a = [1, 2, 3, "xx" => 4, 5];
$b = array_map('triple', $a);
print_r($b);

/*
Array
(
    [0] => 3
    [1] => 6
    [2] => 9
    [xx] => 12
    [4] => 15
)
*/

function a($n, $m)
{
    return "{$n} and {$m}";
}

function b($n, $m)
{
    return [$n => $m];
}

$a = [1, "test" => 2,];
$b = ['aa', 'bb',];

$c = array_map('a', $a, $b);
print_r($c);

$d = array_map('b', $a, $b);
print_r($d);

/*
Array
(
    [0] => 1 and aa
    [1] => 2 and bb
)
Array
(
    [0] => Array
        (
            [1] => aa
        )

    [1] => Array
        (
            [2] => bb
        )

)
*/

// 应用
$integers = array_map ('intval', $integers);
$safeStrings = array_map ('mysql_real_escape_string', $unsafeStrings);