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

$a = array(1, 2, 3, 4);
$b = array_merge(array_slice($a, 0, 2), array(5), array_slice($a, 2));
// $b = array(1, 2, 5, 3, 4)

function insert(&$arr, $value, $index){       
    $lengh = count($arr);
    if($index<0||$index>$lengh)
        return;

    for($i=$lengh; $i>$index; $i--){
        $arr[$i] = $arr[$i-1];
    }

    $arr[$index] = $value;
}

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); 
} 

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。