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_
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
$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, $array, true); // false
array_search() : 在数组中查询给定值(注意,存在是返回该值的键名)
array_filter() : 和array_map() 类似,通过一个回调函数处理数组,但通过函数返回的true或false来决定是否保留此元素
max() : 查询数组中的最大值
min() : 查询数组中的最小值
arsort() : 对数组的键排序,并保持键与值的关系
array_reverse() : 数组反序
sort() : 对数组的值排序,原键名将改变
asort() : 对数组的值排序,并保持键与值的关系
natsort() : 用自然排序算法对数组的值排序,如果有1,0,11,2,21那么结果为0,1,2,11,21
usort() : 使用用户指定的排序函数对数组进行排序
array_multisort() : 对多数组进行排序
shuffle() : 数组元素乱序(很好用的一个函数)
array_unique() : 将值唯一化(即移除重复的元素)
array_walk() : 类似array_map(),也是通过一个回调函数对数组中的每个元素进行处理,区别是array_map()返回一个处理后的结果,array_walk()返回处理是否成功(true or false)。因为这个区别也就决定了array_map()不会改变原数组,array_walk()是对原数组进行处理。
array_walk_recursive() : 对数组中的每个成员递归地应用用户函数
在使用foreach语句时,PHP迭代的是相应数组的一个副本,而非数组本身。在使用each()函数和for语句时,PHP迭代的是原始数组。
遍历数组的四种方式:
foreach ($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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