array_map()

(PHP 4 >= 4.0.6, PHP 5, PHP 7)

为数组的每个元素应用回调函数

说明

array_map()：返回数组，是为$array1每个元素应用$callback函数之后的数组。$callback函数形参的数量和传给array_map()数组数量，两者必须一样。

参数

回调函数，应用到每个数组里的每个元素。

数组，遍历运行$callback函数。

数组列表，每个都遍历运行$callback函数。

返回值

返回数组，包含$callback函数处理之后$array1的所有元素。

范例

Example #1array_map()例子

这使得$b成为：

Array
(
    [0] => 1
    [1] => 8
    [2] => 27
    [3] => 64
    [4] => 125
)

Example #2array_map()使用匿名函数(PHP 5.3.0 起)

Array
(
    [0] => 2
    [1] => 4
    [2] => 6
    [3] => 8
    [4] => 10
)

Example #3array_map()：使用更多的数组

以上例程会输出：

// printout of $c
Array
(
    [0] => The number 1 is called uno in Spanish
    [1] => The number 2 is called dos in Spanish
    [2] => The number 3 is called tres in Spanish
    [3] => The number 4 is called cuatro in Spanish
    [4] => The number 5 is called cinco in Spanish
)
// printout of $d
Array
(
    [0] => Array
        (
            [1] => uno
        )
    [1] => Array
        (
            [2] => dos
        )
    [2] => Array
        (
            [3] => tres
        )
    [3] => Array
        (
            [4] => cuatro
        )
    [4] => Array
        (
            [5] => cinco
        )
)

传入两个及以上的数组时，它们元素数量将会相同。因为回调函数会并行地处理相互对应的元素。如果几个数组的元素数量不一致：空元素会扩展短那个数组，直到长度和最长的数组一样。

此函数有个有趣的用法：传入NULL作为回调函数的名称，将创建多维数组（一个数组，内部包含数组。）

多维数组：创建数组，内部包含数组

以上例程会输出：

Array
(
    [0] => Array
        (
            [0] => 1
            [1] => one
            [2] => uno
        )
    [1] => Array
        (
            [0] => 2
            [1] => two
            [2] => dos
        )
    [2] => Array
        (
            [0] => 3
            [1] => three
            [2] => tres
        )
    [3] => Array
        (
            [0] => 4
            [1] => four
            [2] => cuatro
        )
    [4] => Array
        (
            [0] => 5
            [1] => five
            [2] => cinco
        )
)

如果仅传入一个数组，键（key）会保留；传入多个数组，键（key）是整型数字的序列。

Example #5array_map()键（key）是 string

以上例程会输出：

array(1) {
  ["stringkey"]=>
  array(1) {
    [0]=>
    string(5) "value"
  }
}
array(1) {
  [0]=>
  array(2) {
    [0]=>
    string(5) "value"
    [1]=>
    string(5) "value"
  }
}
array(1) {
  ["stringkey"]=>
  string(5) "value"
}
array(1) {
  [0]=>
  array(2) {
    [0]=>
    string(5) "value"
    [1]=>
    string(5) "value"
  }
}

参见

• array_filter() 用回调函数过滤数组中的单元
• array_reduce() 用回调函数迭代地将数组简化为单一的值
• array_walk() 使用用户自定义函数对数组中的每个元素做回调处理
• callback类型的信息

I was miffed that array_map didn't have a way to pass values *and* keys to the callback, but then I realized I could do this:
function callback($k, $v) { ... }
array_map( "callback", array_keys($array), $array);

If you need to call a static method from array_map, this will NOT work:

Instead, you need to do this:

It is helpful to remember that this will work with any PHP function which expects a callback argument.

PHP 5.3 enables us to use inline anonymous functions with array_map, cleaning up the syntax slightly.

This was possible (although not recommended) in prior versions of PHP 5, via create_function().

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