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PHP逆放数组和置换数组键和值详解

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Jun 13, 2016 pm 12:03 PM

arraydelawarejerseyPennsylvania

PHP逆置数组和置换数组键和值详解

逆置数组元素顺序

array_reverse() 函数将数组中元素的顺序逆置。其形式如下:

array array_reverse(array array [, boolean preserve_keys])

如果可选参数preserve_keys设置为TRUE ，则保持键映射。否则，重新摆放后的各个值将对应于先

前该位置上的相应键z

$states = array("Delaware" , "Pennsylvania" , "New Jersey");print_r(array_reverse($states));// Array ( [0] => New Jersey [1] => Pennsylvania [2] => Delaware )

可以与启用preserve_keys 时得到的结果做个比较

$states = array("Delaware" , "Pennsylvania" , "New Jersey");print_r(array_reverse($states, 1));// Array ( [2] => New Jersey [1] => Pennsylvania [0] => Delaware )

使用关联键的数组将不受preserve_keys 的影响，对于关联数组，总是会保持键映射。

置换数组键和值

array_fl ip() 函数将置换数组中键及其相应值的角色。其形式如下z

array array_flip(array array)

下面是这个函数的一个例子z

$state = array("Delaware" ,"Pennsylvania" , "New Jersey");$state = array_flip($state);print_r($state);

这个例子返回以下结果z

Array ( [Delaware] => 0 [Pennsylvania].=> 1 [New Jersey] => 2 )

【授之以渔】详细教程请参见【PHP与mysql程序设计】这本的第52页，OK书屋（www.okpdf.com）提供免费电子书下载地址:点击下载

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