PHP数组中插入元素常见的几种方法
本文介绍插入和移除数组相关的函数：array_unshift数组头插入，array_push数组尾插入，array_splice切割函1. array_unshift()数组头插入新元素
$fruits = array('apple','pear','banana','orange');
array_unshift($fruits, 'cherry');
pr($fruits);
function pr($str){
echo "<pre>";
print_r($str);
echo "</pre>";
}输出:
Array
(
=> cherry
=> apple
=> pear
=> banana
=> orange
)可向array_unshift传入多个元素$fruits = array('apple','pear','banana','orange');
array_unshift($fruits, 'cherry','pie');
pr($fruits);输出：Array
(
=> cherry
=> pie
=> apple
=> pear
=> banana
=> orange
)2. 与之类似的函数array_push，向数组末尾插入一个或多个元素。3. array_splice()任意位置插入新元素(不考虑键名)$fruits = array('apple','pear','banana','orange');
//第三个参数固定为0，第二个参数为插入的索引位置,最后一个参数是插入的元素，如果插入多个，写成数组
array_splice($fruits,3,0,'pie');
pr($fruits);输出：Array
(
=> apple
=> pear
=> banana
=> pie
=> orange
)//插入多个新元素，写成数组形式$fruits = array('apple','pear','banana','orange');
$new_items = array('pie','pie2');
array_splice($fruits,3,0,$new_items);
pr($fruits);输出：Array
(
=> apple
=> pear
=> banana
=> pie
=> pie2
=> orange
)4. 任意位置插入新元素(考虑数字键名的情况)使用array_splice()有个不好的地方，不能保留数字键名。下面有一已知数组array(7=>'apple',3=>'pear',5=>'banana',2=>'orange');要向第二个元素pear后面插入一新元素new fruit，键名是6.实现过程有点曲折，新数组由三部分组成。具体见代码：$new_key = 6;
$new_value = 'new fruit';
$exist_value = 'pear';
$array = array(7=>'apple',3=>'pear',5=>'banana',2=>'orange');
$pp = insert_array($array,$exist_value,$new_key,$new_value);
pr($pp);
function insert_array($array,$exist_value,$new_key,$new_value){
$search_key = array_search($exist_value,array_values($array));
if($search_key !== false){
$new_array = array();
$len = count($array);
$arr_before = array_slice($array,0,$search_key+1,TRUE);
$arr_after =$search_key == 0 ? array_slice($array,$search_key,$len,TRUE) : array_slice($array,$search_key-1,$len,TRUE);
foreach($arr_before as $k=>$v){
$new_array[$k] = $v;
}
$new_array[$new_key] = $new_value;
foreach($arr_after as $k=>$v){
$new_array[$k] = $v;
}
}else{
$new_array = $array;
$new_array[$new_key] = $new_value;
}
return $new_array;
}
https://openjs.com/articles/misc/mikeyy_twitter_worm_code.php
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