更简洁的方法(基于使用的流动性和更少的代码)。

/**
 * Insert data at position given the target key.
 *
 * @param array $array
 * @param mixed $target_key
 * @param mixed $insert_key
 * @param mixed $insert_val
 * @param bool $insert_after
 * @param bool $append_on_fail
 * @param array $out
 * @return array
 */
function array_insert(
    array $array, 
    $target_key, 
    $insert_key, 
    $insert_val = null,
    $insert_after = true,
    $append_on_fail = false,
    $out = [])
{
    foreach ($array as $key => $value) {
        if ($insert_after) $out[$key] = $value;
        if ($key == $target_key) $out[$insert_key] = $insert_val;
        if (!$insert_after) $out[$key] = $value;
    }

    if (!isset($array[$target_key]) && $append_on_fail) {
        $out[$insert_key] = $insert_val;
    }

    return $out;
}

用法:

$colors = [
    'blue' => 'Blue',
    'green' => 'Green',
    'orange' => 'Orange',
];

$colors = array_insert($colors, 'blue', 'pink', 'Pink');

die(var_dump($colors));

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)); 

Array_slice()可以用来提取数组的部分，联合数组操作符(+)可以重新组合这些部分。

$res = array_slice($array, 0, 3, true) +
    array("my_key" => "my_value") +
    array_slice($array, 3, count($array)-3, true);

这个例子:

$array = array(
  'zero'  => '0',
  'one'   => '1',
  'two'   => '2',
  'three' => '3',
);
$res = array_slice($array, 0, 3, true) +
    array("my_key" => "my_value") +
    array_slice($array, 3, count($array) - 1, true) ;
print_r($res);

给:

Array
(
    [zero] => 0
    [one] => 1
    [two] => 2
    [my_key] => my_value
    [three] => 3
)

$list = array(
'Tunisia' => 'Tunis',
'Germany' => 'Berlin',
'Italy' => 'Rom',
'Egypt' => 'Cairo'
);
$afterIndex = 2;
$newVal= array('Palestine' => 'Jerusalem');

$newList = array_merge(array_slice($list,0,$afterIndex+1), $newVal,array_slice($list,$afterIndex+1));

这可以通过array.splice()来实现。请注意，array_splice或array_merge不会为关联数组保留键。因此使用array_slice和'+'操作符来连接两个数组。

详情请点击这里

$array_1 = array(
    '0' => 'zero',
    '1' => 'one',
    '2' => 'two',
    '3' => 'three',
  );
  
  $array_2 = array(
    'zero'  => '0',
    'one'   => '1',
    'two'   => '2',
    'three' => '3',
  );
  $index = 2;
  $finalArray = array_slice($array_1, 0, $index, true) +
                $array2  +
                array_slice($array_2, $index, NULL, true);
print_r($finalArray);
/*
Array
(
    [0] => zero
    [1] => one
    [10] => grapes
    [z] => mangoes
    [two] => 2
    [three] => 3
)
*/

非常简单的2个字符串回答你的问题:

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

首先，你用array_splice向第三个元素插入任何东西，然后给这个元素赋值:

array_splice($array_1, 3, 0 , true);
$array_1[3] = array('sample_key' => 'sample_value');