对于第一个数组，使用array_splice():

$array_1 = array(
  '0' => 'zero',
  '1' => 'one',
  '2' => 'two',
  '3' => 'three',
);

array_splice($array_1, 3, 0, 'more');
print_r($array_1);

输出:

Array(
    [0] => zero
    [1] => one
    [2] => two
    [3] => more
    [4] => three
)

对于第二个，没有顺序，所以你只需要做:

$array_2['more'] = '2.5';
print_r($array_2);

把钥匙按你想要的排序。

我这样做

    $slightly_damaged = array_merge(
        array_slice($slightly_damaged, 0, 4, true) + ["4" => "0.0"], 
        array_slice($slightly_damaged, 4, count($slightly_damaged) - 4, true)
    );

对于第一个数组，使用array_splice():

$array_1 = array(
  '0' => 'zero',
  '1' => 'one',
  '2' => 'two',
  '3' => 'three',
);

array_splice($array_1, 3, 0, 'more');
print_r($array_1);

输出:

Array(
    [0] => zero
    [1] => one
    [2] => two
    [3] => more
    [4] => three
)

对于第二个，没有顺序，所以你只需要做:

$array_2['more'] = '2.5';
print_r($array_2);

把钥匙按你想要的排序。

代码:

function insertValueAtPosition($arr, $insertedArray, $position) {
    $i = 0;
    $new_array=[];
    foreach ($arr as $key => $value) {
        if ($i == $position) {
            foreach ($insertedArray as $ikey => $ivalue) {
                $new_array[$ikey] = $ivalue;
            }
        }
        $new_array[$key] = $value;
        $i++;
    }
    return $new_array;
}

例子:

$array        = ["A"=8, "K"=>3];
$insert_array = ["D"= 9];

insertValueAtPosition($array, $insert_array, $position=2);
// result ====> ["A"=>8,  "D"=>9,  "K"=>3];

也许看起来不完美，但很有效。

我刚刚创建了一个ArrayHelper类，它可以使数值索引变得非常容易。

class ArrayHelper
{
    /*
        Inserts a value at the given position or throws an exception if
        the position is out of range.
        This function will push the current values up in index. ex. if 
        you insert at index 1 then the previous value at index 1 will 
        be pushed to index 2 and so on.
        $pos: The position where the inserted value should be placed. 
        Starts at 0.
    */
    public static function insertValueAtPos(array &$array, $pos, $value) {
        $maxIndex = count($array)-1;

        if ($pos === 0) {
            array_unshift($array, $value);
        } elseif (($pos > 0) && ($pos <= $maxIndex)) {
            $firstHalf = array_slice($array, 0, $pos);
            $secondHalf = array_slice($array, $pos);
            $array = array_merge($firstHalf, array($value), $secondHalf);
        } else {
            throw new IndexOutOfBoundsException();
        }

    }
}

例子:

$array = array('a', 'b', 'c', 'd', 'e');
$insertValue = 'insert';
\ArrayHelper::insertValueAtPos($array, 3, $insertValue);

开始$数组:

Array ( 
    [0] => a 
    [1] => b 
    [2] => c 
    [3] => d 
    [4] => e 
)

结果:

Array ( 
    [0] => a 
    [1] => b 
    [2] => c 
    [3] => insert 
    [4] => d 
    [5] => e 
)

不像Artefacto的答案那么具体，但基于他使用array_slice()的建议，我写了下一个函数:

function arrayInsert($target, $byKey, $byOffset, $valuesToInsert, $afterKey) {
    if (isset($byKey)) {
        if (is_numeric($byKey)) $byKey = (int)floor($byKey);
        $offset = 0;

        foreach ($target as $key => $value) {
            if ($key === $byKey) break;
            $offset++;
        }

        if ($afterKey) $offset++;
    } else {
        $offset = $byOffset;
    }

    $targetLength = count($target);
    $targetA = array_slice($target, 0, $offset, true);
    $targetB = array_slice($target, $offset, $targetLength, true);
    return array_merge($targetA, $valuesToInsert, $targetB);
}

特点:

插入一个或múltiple值 插入键值对 在键前/键后插入，或按偏移量插入

使用例子:

$target = [
    'banana' => 12,
    'potatoe' => 6,
    'watermelon' => 8,
    'apple' => 7,
    2 => 21,
    'pear' => 6
];

// Values must be nested in an array
$insertValues = [
    'orange' => 0,
    'lemon' => 3,
    3
];

// By key
// Third parameter is not applicable
//     Insert after 2 (before 'pear')
var_dump(arrayInsert($target, 2, null, $valuesToInsert, true));
//     Insert before 'watermelon'
var_dump(arrayInsert($target, 'watermelon', null, $valuesToInsert, false)); 

// By offset
// Second and last parameter are not applicable
//     Insert in position 2 (zero based i.e. before 'watermelon')
var_dump(arrayInsert($target, null, 2, $valuesToInsert, null));