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PHP: array_map - Manual
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array_keysarray_map
(PHP 4 >= 4.0.6, PHP 5)
array_map — 将回调函数作用到给定数组的单元上
说明
array array_map ( callback $callback , array $arr1 [, array $... ] )
array_map() 返回一个数组，该数组包含了 arr1 中的所有单元经过 callback 作用过之后的单元。 callback 接受的参数数目应该和传递给 array_map() 函数的数组数目一致。
Example#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 );
?> 这使得 $b 成为：
Array
(
[0] => 1
[1] => 8
[2] => 27
[3] => 64
[4] => 125
)
Example#2 array_map() - 使用更多的数组
<?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 );
?> 上例将输出：
// 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
)
)
通常使用了两个或更多数组时，它们的长度应该相同，因为回调函数是平行作用于相应的单元上的。如果数组的长度不同，则最短的一个将被用空的单元扩充。
本函数一个有趣的用法是构造一个数组的数组，这可以很容易的通过用 NULL 作为回调函数名来实现。
Example#3 建立一个数组的数组
<?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 );
?> 上例将输出：
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
)
)
参见 array_filter()， array_reduce()， array_walk() 和有关 callback 类型的信息。
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