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array_map (PHP 4 >= 4.0.6, PHP 5) array_map --
將回呼函數作用到給定陣列的單元上
說明array array_map ( callback callback, array arr1 [, array ...] )
array_map() 返回一個陣列，該陣列包括了
arr1 中的所有單元經由
callback 作用過之後的單元。callback
接受的參數數目應該和傳遞給
array_map() 函數的陣列數目一致。
例子 1. array_map() 例子
<?php
function cube($n)
{
return($n * $n * $n);
}
$a = array(1, 2, 3, 4, 5);
$b = array_map("cube", $a);
print_r($b);
?>
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這使得 $b 成為：
Array
(
[0] => 1
[1] => 8
[2] => 27
[3] => 64
[4] => 125
) |
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例子 2. array_map() - 使用更多的陣列
<?php
function show_Spanish($n, $m)
{
return("The number $n is called $m in Spanish");
}
function map_Spanish($n, $m)
{
return(array($n => $m));
}
$a = array(1, 2, 3, 4, 5);
$b = array("uno", "dos", "tres", "cuatro", "cinco");
$c = array_map("show_Spanish", $a, $b);
print_r($c);
$d = array_map("map_Spanish", $a , $b);
print_r($d);
?>
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上例將輸出： // 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
)
) |
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通常使用了兩個或更多陣列時，它們的長度應該相同，因為回呼函數是平行作用於相應的單元上的。若果陣列的長度不同，則最短的一個將被用空的單元擴充。
本函數一個有趣的用法是構造一個陣列的陣列，這可以很容易的通過用 NULL 作為回呼函數名來實現。
例子 3. 建立一個陣列的陣列
<?php
$a = array(1, 2, 3, 4, 5);
$b = array("one", "two", "three", "four", "five");
$c = array("uno", "dos", "tres", "cuatro", "cinco");
$d = array_map(null, $a, $b, $c);
print_r($d);
?>
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上例將輸出： 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
)
) |
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參見 array_filter()，array_reduce()，array_walk()
和有關 callback 類型的訊息。
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