杰伊的解决方案。李是完美的。如果要向多维数组中添加项，请先添加一个一维数组，然后再替换它。

$original = (
[0] => Array
    (
        [title] => Speed
        [width] => 14
    )

[1] => Array
    (
        [title] => Date
        [width] => 18
    )

[2] => Array
    (
        [title] => Pineapple
        [width] => 30
     )
)

将相同格式的项添加到此数组中将添加所有新的数组索引作为项，而不仅仅是项。

$new = array(
    'title' => 'Time',
    'width' => 10
);
array_splice($original,1,0,array('random_string')); // can be more items
$original[1] = $new;  // replaced with actual item

注意:使用array_splice直接向多维数组添加项会将其所有索引作为项添加，而不仅仅是该项。

你可以试试，用这个方法让它变得简单

/**
 * array insert element on position
 * 
 * @link https://vector.cool
 * 
 * @since 1.01.38
 *
 * @param array $original
 * @param mixed $inserted
 * @param int   $position
 * @return array
 */
function array_insert(&$original, $inserted, int $position): array
{
    array_splice($original, $position, 0, array($inserted));
    return $original;
}


$columns = [
    ['name' => '預約項目', 'column' => 'item_name'],
    ['name' => '預約時間', 'column' => 'start_time'],
    ['name' => '預約姓名', 'column' => 'full_name'],
    ['name' => '連絡電話', 'column' => 'phone'],
    ['name' => '建立時間', 'column' => 'create_time']
];
$col = ['name' => '預約帳戶', 'column' => 'user_id'];
$columns = array_insert($columns, $col, 3);
print_r($columns);

打印:

Array
(
    [0] => Array
        (
            [name] => 預約項目
            [column] => item_name
        )
    [1] => Array
        (
            [name] => 預約時間
            [column] => start_time
        )
    [2] => Array
        (
            [name] => 預約姓名
            [column] => full_name
        )
    [3] => Array
        (
            [name] => 報名人數1
            [column] => num_of_people
        )
    [4] => Array
        (
            [name] => 連絡電話
            [column] => phone
        )
    [5] => Array
        (
            [name] => 預約帳戶
            [column] => user_id
        )
    [6] => Array
        (
            [name] => 建立時間
            [column] => create_time
        )
)

在做了几天之后，这是我能找到的最简单的解决方案。

$indexnumbertoaddat // this is a variable that points to the index # where you 
want the new array to be inserted

$arrayToAdd = array(array('key' => $value, 'key' => $value)); //this is the new 
 array and it's values that you want to add. //the key here is to write it like 
 array(array('key' =>, since you're adding this array inside another array. This 
 is the point that a lot of answer left out. 

array_splice($originalArray, $indexnumbertoaddatt, 0, $arrayToAdd); //the actual 
splice function. You're doing it to $originalArray, at the index # you define, 
0 means you're just shifting all other index items down 1, and then you add the 
new array. 

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);
}

可以在整数和字符串位置进行插入的函数:

/**
 * @param array      $array
 * @param int|string $position
 * @param mixed      $insert
 */
function array_insert(&$array, $position, $insert)
{
    if (is_int($position)) {
        array_splice($array, $position, 0, $insert);
    } else {
        $pos   = array_search($position, array_keys($array));
        $array = array_merge(
            array_slice($array, 0, $pos),
            $insert,
            array_slice($array, $pos)
        );
    }
}

整数的用法:

$arr = ["one", "two", "three"];
array_insert(
    $arr,
    1,
    "one-half"
);
// ->
array (
  0 => 'one',
  1 => 'one-half',
  2 => 'two',
  3 => 'three',
)

字符串的用法:

$arr = [
    "name"  => [
        "type"      => "string",
        "maxlength" => "30",
    ],
    "email" => [
        "type"      => "email",
        "maxlength" => "150",
    ],
];

array_insert(
    $arr,
    "email",
    [
        "phone" => [
            "type"   => "string",
            "format" => "phone",
        ],
    ]
);
// ->
array (
  'name' =>
  array (
    'type' => 'string',
    'maxlength' => '30',
  ),
  'phone' =>
  array (
    'type' => 'string',
    'format' => 'phone',
  ),
  'email' =>
  array (
    'type' => 'email',
    'maxlength' => '150',
  ),
)

这可以通过array_splice完成，但是，当插入数组或使用字符串键时，array_splice会失败。我写了一个函数来处理所有情况:

function array_insert(&$arr, $index, $val)
{
    if (is_string($index))
        $index = array_search($index, array_keys($arr));
    if (is_array($val))
        array_splice($arr, $index, 0, [$index => $val]);
    else
        array_splice($arr, $index, 0, $val);
}