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;
}

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)
    );

试试这个===

$key_pos=0;
$a1=array("a"=>"red", "b"=>"green", "c"=>"blue", "d"=>"yellow");
$arrkey=array_keys($a1);
array_walk($arrkey,function($val,$key) use(&$key_pos) {
  if($val=='b')
    {
        $key_pos=$key;
    }
  });
$a2=array("e"=>"purple");
$newArray = array_slice($a1, 0, $key_pos, true) + $a2 +
        array_slice($a1, $key_pos, NULL, true);
print_r($newArray);

输出

Array (
      [a] => red
      [e] => purple
      [b] => green
      [c] => blue
      [d] => yellow )

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)); 

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
)