以下是我的看法:

/**
 * 
 * Insert an element after an index in an array
 * @param array $array  
 * @param string|int $key 
 * @param mixed $value
 * @param string|int $offset
 * @return mixed
 */
function array_splice_associative($array, $key, $value, $offset) {
    if (!is_array($array)) {
        return $array;
    }
    if (array_key_exists($key, $array)) {
        unset($array[$key]);
    }
    $return = array();
    $inserted = false;
    foreach ($array as $k => $v) {
        $return[$k] = $v;
        if ($k == $offset && !$inserted) {
            $return[$key] = $value;
            $inserted = true;
        }
    }
    if (!$inserted) {
        $return[$key] = $value;
    }


    return $return;
}

这是一个老问题，但我在2014年发表了一篇评论，经常回到这个问题。我想我应该留下一个完整的答案。这不是最短的解决方案，但很容易理解。

在关联数组中插入一个新值，在有编号的位置，保留键并保持顺序。

$columns = array(
    'id' => 'ID',
    'name' => 'Name',
    'email' => 'Email',
    'count' => 'Number of posts'
);

$columns = array_merge(
    array_slice( $columns, 0, 3, true ),     // The first 3 items from the old array
    array( 'subscribed' => 'Subscribed' ),   // New value to add after the 3rd item
    array_slice( $columns, 3, null, true )   // Other items after the 3rd
);

print_r( $columns );

/*
Array ( 
    [id] => ID 
    [name] => Name 
    [email] => Email 
    [subscribed] => Subscribed 
    [count] => Number of posts 
)
*/

这是一种更好的方法，如何在数组的某个位置插入项目。

function arrayInsert($array, $item, $position)
{
    $begin = array_slice($array, 0, $position);
    array_push($begin, $item);
    $end = array_slice($array, $position);
    $resultArray = array_merge($begin, $end);
    return $resultArray;
}

最简单的解决方案，如果你想在某个键后插入(一个元素或数组):

function array_splice_after_key($array, $key, $array_to_insert)
{
    $key_pos = array_search($key, array_keys($array));
    if($key_pos !== false){
        $key_pos++;
        $second_array = array_splice($array, $key_pos);
        $array = array_merge($array, $array_to_insert, $second_array);
    }
    return $array;
}

如果你有:

$array = [
    'one' => 1,
    'three' => 3
];
$array_to_insert = ['two' => 2];

和执行:

$result_array = array_splice_after_key($array, 'one', $array_to_insert);

你会有:

Array ( 
    ['one'] => 1 
    ['two'] => 2 
    ['three'] => 3 
)

这里有一个你可以使用的简单函数。只要插进去就行了。

这是按索引插入，而不是按值插入。

您可以选择传递该数组，或者使用已经声明的数组。

较新的、较短的版本:

   function insert($array, $index, $val)
   {
       $size = count($array); //because I am going to use this more than one time
       if (!is_int($index) || $index < 0 || $index > $size)
       {
           return -1;
       }
       else
       {
           $temp   = array_slice($array, 0, $index);
           $temp[] = $val;
           return array_merge($temp, array_slice($array, $index, $size));
       }
   }

更老、更长的版本:

  function insert($array, $index, $val) { //function decleration
    $temp = array(); // this temp array will hold the value 
    $size = count($array); //because I am going to use this more than one time
    // Validation -- validate if index value is proper (you can omit this part)       
        if (!is_int($index) || $index < 0 || $index > $size) {
            echo "Error: Wrong index at Insert. Index: " . $index . " Current Size: " . $size;
            echo "<br/>";
            return false;
        }    
    //here is the actual insertion code
    //slice part of the array from 0 to insertion index
    $temp = array_slice($array, 0, $index);//e.g index=5, then slice will result elements [0-4]
    //add the value at the end of the temp array// at the insertion index e.g 5
    array_push($temp, $val);
    //reconnect the remaining part of the array to the current temp
    $temp = array_merge($temp, array_slice($array, $index, $size)); 
    $array = $temp;//swap// no need for this if you pass the array cuz you can simply return $temp, but, if u r using a class array for example, this is useful. 
  
     return $array; // you can return $temp instead if you don't use class array
}

使用的例子:

//1
$result = insert(array(1,2,3,4,5),0, 0);
echo "<pre>";
echo "<br/>";
print_r($result);
echo "</pre>";
//2
$result = insert(array(1,2,3,4,5),2, "a");
echo "<pre>";
print_r($result);
echo "</pre>";
//3
$result = insert(array(1,2,3,4,5) ,4, "b");
echo "<pre>";
print_r($result);
echo "</pre>";
//4
$result = insert(array(1,2,3,4,5),5, 6);
echo "<pre>";
echo "<br/>";
print_r($result);
echo "</pre>";

预期结果:

//1
Array
(
    [0] => 0
    [1] => 1
    [2] => 2
    [3] => 3
    [4] => 4
    [5] => 5
)
//2
Array
(
    [0] => 1
    [1] => 2
    [2] => a
    [3] => 3
    [4] => 4
    [5] => 5
)
//3
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => b
    [5] => 5
)

//4
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
)

这是PHP 7.1中的另一个解决方案

     /**
     * @param array $input    Input array to add items to
     * @param array $items    Items to insert (as an array)
     * @param int   $position Position to inject items from (starts from 0)
     *
     * @return array
     */
    function arrayInject( array $input, array $items, int $position ): array 
    {
        if (0 >= $position) {
            return array_merge($items, $input);
        }
        if ($position >= count($input)) {
            return array_merge($input, $items);
        }

        return array_merge(
            array_slice($input, 0, $position, true),
            $items,
            array_slice($input, $position, null, true)
        );
    }