如何将一个新项目插入到数组的任何位置,例如在数组的中间?
当前回答
要将元素插入到具有字符串键的数组中,您可以这样做:
/* insert an element after given array key
* $src = array() array to work with
* $ins = array() to insert in key=>array format
* $pos = key that $ins will be inserted after
*/
function array_insert_string_keys($src,$ins,$pos) {
$counter=1;
foreach($src as $key=>$s){
if($key==$pos){
break;
}
$counter++;
}
$array_head = array_slice($src,0,$counter);
$array_tail = array_slice($src,$counter);
$src = array_merge($array_head, $ins);
$src = array_merge($src, $array_tail);
return($src);
}
其他回答
在数组开头添加元素的提示:
$a = array('first', 'second');
$a[-1] = 'i am the new first element';
然后:
foreach($a as $aelem)
echo $a . ' ';
//returns first, second, i am...
but:
for ($i = -1; $i < count($a)-1; $i++)
echo $a . ' ';
//returns i am as 1st element
$result_array = array();
$array = array("Tim","John","Mark");
$new_element = "Bill";
$position = 1;
for ($i=0; $i<count($array); $i++)
{
if ($i==$position)
{
$result_array[] = $new_element;
}
$result_array[] = $array[$i];
}
print_r($result_array);
// Result will Array([0] => "Tim",[1] => "Bill", [2] => "John",[1] => "Mark")
如果你有正则数组,没有什么特别的,这就可以了。记住,使用array_splice()插入元素实际上意味着在开始索引之前插入。移动元素时要小心,因为向上移动意味着$targetIndex -1,向下移动意味着$targetIndex + 1。
class someArrayClass
{
private const KEEP_EXISTING_ELEMENTS = 0;
public function insertAfter(array $array, int $startIndex, $newElements)
{
return $this->insertBefore($array, $startIndex + 1, $newElements);
}
public function insertBefore(array $array, int $startIndex, $newElements)
{
return array_splice($array, $startIndex, self::KEEP_EXISTING_ELEMENTS, $newElements);
}
}
如果你想保留初始数组的键,并添加一个有键的数组,那么使用下面的函数:
function insertArrayAtPosition( $array, $insert, $position ) {
/*
$array : The initial array i want to modify
$insert : the new array i want to add, eg array('key' => 'value') or array('value')
$position : the position where the new array will be inserted into. Please mind that arrays start at 0
*/
return array_slice($array, 0, $position, TRUE) + $insert + array_slice($array, $position, NULL, TRUE);
}
电话的例子:
$array = insertArrayAtPosition($array, array('key' => 'Value'), 3);
这样你就可以插入数组:
function array_insert(&$array, $value, $index)
{
return $array = array_merge(array_splice($array, max(0, $index - 1)), array($value), $array);
}