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PHP Cookbook读书笔记 – 第04章数组

Jun 06, 2016 pm 07:40 PM
php array yes notes read

数组 是在web开发中经常会用到的部分,所以此章节的内容比较重要 unset() : 销毁一个变量(当然也包括 数组 ) array_pad() : 用值填补指定长度的空缺 array_splice() : 除了可以通过此函数移除 数组 中的元素,还可以指定另一个 数组 替换移除的部分 array_

PHP Cookbook读书笔记 – 第04章数组数组是在web开发中经常会用到的部分,所以此章节的内容比较重要
unset() : 销毁一个变量(当然也包括数组
array_pad() : 用值填补指定长度的空缺
array_splice() : 除了可以通过此函数移除数组中的元素,还可以指定另一个数组替换移除的部分
array_merge() : 合并多个数组
array_push() : 在数组末尾添加值
array_map() : 通过一个回调函数处理数组中的多个元素
is_array() : 检测一个变量是否是数组类型

array_shift() : 移除数组中的第一个元素
array_pop() : 返回数组中的最后一个元素并将其从原数组中移除
join() : 之前章节介绍过,将数组按其指定的分隔符合并为一个字符串
array_key_exists() : 查询数组中是否包含某键名
in_array() : 查询某个值是否在数组中(返回布尔值)

in_array 容易出错的地方

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$array = array(1, '2', 'three');

 

in_array(0, $array);        // true!

in_array(0, $array, true);  // false

in_array(1, $array);        // true

in_array(1, $array, true);  // true

in_array(2, $array);        // true

in_array(2, $array, true);  // false

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array_search() : 在数组中查询给定值(注意,存在是返回该值的键名

array_filter() : 和array_map() 类似,通过一个回调函数处理数组,但通过函数返回的true或false来决定是否保留此元素

max() : 查询数组中的最大值

min() : 查询数组中的最小值

arsort() : 对数组的键排序,并保持键与值的关系

array_reverse() : 数组反序

sort() : 对数组的值排序,原键名将改变

asort() : 对数组的值排序,并保持键与值的关系

natsort() : 用自然排序算法对数组的值排序,如果有1,0,11,2,21那么结果为0,1,2,11,21

usort() : 使用用户指定的排序函数对数组进行排序

array_multisort() : 对多数组进行排序

shuffle() : 数组元素乱序(很好用的一个函数)

array_unique() : 将值唯一化(即移除重复的元素)

array_walk() : 类似array_map(),也是通过一个回调函数对数组中的每个元素进行处理,区别是array_map()返回一个处理后的结果,array_walk()返回处理是否成功(true or false)。因为这个区别也就决定了array_map()不会改变原数组,array_walk()是对原数组进行处理。

array_walk_recursive() : 对数组中的每个成员递归地应用用户函数

在使用foreach语句时,PHP迭代的是相应数组的一个副本,而非数组本身。在使用each()函数和for语句时,PHP迭代的是原始数组

遍历数组的四种方式:

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foreach ($array as $value) {

    // Act on $value

}

 

foreach ($array as $key => $value) {

    // Act II

}

 

for ($key = 0, $size = count($array); $key

<p><strong>数组</strong>中集合的运用</p>

<pre class="brush:php;toolbar:false">//并集

$union = array_unique(array_merge($a, $b));

//交集

$interdiv = array_intersect($a, $b);

//差集

$difference = array_diff($a, $b);

//对称差集

$difference = array_merge(array_diff($a, $b), array_diff($b, $a));

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