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How to add elements to php array
1. array_unshift() inserts new elements into the array head
$fruits = array('apple','pear','banana','orange'); array_unshift($fruits, 'cherry'); pr($fruits); function pr($str){ echo "<pre class="brush:php;toolbar:false">"; print_r($str); echo ""; }
Output:
Array( [0] => cherry [1] => apple [2] => pear [3] => banana [4] => orange )
Multiple elements can be passed to array_unshift
$fruits = array('apple','pear','banana','orange'); array_unshift($fruits, 'cherry','pie'); pr($fruits);
Output:
Array( [0] => cherry [1] => pie [2] => apple [3] => pear [4] => banana [5] => orange )
2. The similar function array_push inserts one or more elements to the end of the array element.
3. array_splice() inserts new elements at any position (regardless of key names)
$fruits = array('apple','pear','banana','orange'); //第三个参数固定为0,第二个参数为插入的索引位置,最后一个参数是插入的元素,如果插入多个,写成数组 array_splice($fruits,3,0,'pie'); pr($fruits);
Output:
Array( [0] => apple [1] => pear [2] => banana [3] => pie [4] => orange )
//Insert multiple new elements, written in array form
$fruits = array('apple','pear','banana','orange');$new_items = array('pie','pie2'); array_splice($fruits,3,0,$new_items); pr($fruits);
Output:
Array( [0] => apple [1] => pear [2] => banana [3] => pie [4] => pie2 [5] => orange )
4. Insert new elements at any position (considering the case of numeric key names)
There is a disadvantage in using array_splice(), it cannot retain numbers. Key name.
There is a known array below
array(7=>'apple',3=>'pear',5=>'banana',2=>'orange');
To insert a new element new fruit after the second element pear, the key name is 6.
The implementation process is a bit tortuous, new The array consists of three parts. See the code for details:
$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; }
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