假设我们有两个数组:
$array_1 = array(
'0' => 'zero',
'1' => 'one',
'2' => 'two',
'3' => 'three',
);
$array_2 = array(
'zero' => '0',
'one' => '1',
'two' => '2',
'three' => '3',
);
现在，我想在每个数组的第三个元素后插入数组('sample_key' => 'sample_value')。我该怎么做呢?
当前回答
这里有一个你可以使用的简单函数。只要插进去就行了。
这是按索引插入，而不是按值插入。
您可以选择传递该数组，或者使用已经声明的数组。
较新的、较短的版本:
function insert($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
)
其他回答
如果你不知道你想在位置3插入它，但你知道你想在后面插入它的键，在看到这个问题后，我想出了这个小函数。
/**
* Inserts any number of scalars or arrays at the point
* in the haystack immediately after the search key ($needle) was found,
* or at the end if the needle is not found or not supplied.
* Modifies $haystack in place.
* @param array &$haystack the associative array to search. This will be modified by the function
* @param string $needle the key to search for
* @param mixed $stuff one or more arrays or scalars to be inserted into $haystack
* @return int the index at which $needle was found
*/
function array_insert_after(&$haystack, $needle = '', $stuff){
if (! is_array($haystack) ) return $haystack;
$new_array = array();
for ($i = 2; $i < func_num_args(); ++$i){
$arg = func_get_arg($i);
if (is_array($arg)) $new_array = array_merge($new_array, $arg);
else $new_array[] = $arg;
}
$i = 0;
foreach($haystack as $key => $value){
++$i;
if ($key == $needle) break;
}
$haystack = array_merge(array_slice($haystack, 0, $i, true), $new_array, array_slice($haystack, $i, null, true));
return $i;
}
这里是一个代码板小提琴看到它的行动:http://codepad.org/5WlKFKfz
注意:array_splice()会比array_merge(array_slice())更有效，但这样你插入的数组的键就会丢失。叹息。
这是PHP 7.1中的另一个解决方案
/**
* @param array $input Input array to add items to
* @param array $items Items to insert (as an array)
* @param int $position Position to inject items from (starts from 0)
*
* @return array
*/
function arrayInject( array $input, array $items, int $position ): array
{
if (0 >= $position) {
return array_merge($items, $input);
}
if ($position >= count($input)) {
return array_merge($input, $items);
}
return array_merge(
array_slice($input, 0, $position, true),
$items,
array_slice($input, $position, null, true)
);
}
我最近写了一个函数来做一些类似于你正在尝试的事情，这与clasvdb的答案类似。
function magic_insert($index,$value,$input_array ) {
if (isset($input_array[$index])) {
$output_array = array($index=>$value);
foreach($input_array as $k=>$v) {
if ($k<$index) {
$output_array[$k] = $v;
} else {
if (isset($output_array[$k]) ) {
$output_array[$k+1] = $v;
} else {
$output_array[$k] = $v;
}
}
}
} else {
$output_array = $input_array;
$output_array[$index] = $value;
}
ksort($output_array);
return $output_array;
}
基本上，它在一个特定的点插入，但通过向下移动所有项来避免覆盖。
该函数支持:
数字键和关联键 在建立键之前或之后插入 如果key未建立，则附加到数组末尾
function insert_into_array( $array, $search_key, $insert_key, $insert_value, $insert_after_founded_key = true, $append_if_not_found = false ) {
$new_array = array();
foreach( $array as $key => $value ){
// INSERT BEFORE THE CURRENT KEY?
// ONLY IF CURRENT KEY IS THE KEY WE ARE SEARCHING FOR, AND WE WANT TO INSERT BEFORE THAT FOUNDED KEY
if( $key === $search_key && ! $insert_after_founded_key )
$new_array[ $insert_key ] = $insert_value;
// COPY THE CURRENT KEY/VALUE FROM OLD ARRAY TO A NEW ARRAY
$new_array[ $key ] = $value;
// INSERT AFTER THE CURRENT KEY?
// ONLY IF CURRENT KEY IS THE KEY WE ARE SEARCHING FOR, AND WE WANT TO INSERT AFTER THAT FOUNDED KEY
if( $key === $search_key && $insert_after_founded_key )
$new_array[ $insert_key ] = $insert_value;
}
// APPEND IF KEY ISNT FOUNDED
if( $append_if_not_found && count( $array ) == count( $new_array ) )
$new_array[ $insert_key ] = $insert_value;
return $new_array;
}
用法:
$array1 = array(
0 => 'zero',
1 => 'one',
2 => 'two',
3 => 'three',
4 => 'four'
);
$array2 = array(
'zero' => '# 0',
'one' => '# 1',
'two' => '# 2',
'three' => '# 3',
'four' => '# 4'
);
$array3 = array(
0 => 'zero',
1 => 'one',
64 => '64',
3 => 'three',
4 => 'four'
);
// INSERT AFTER WITH NUMERIC KEYS
print_r( insert_into_array( $array1, 3, 'three+', 'three+ value') );
// INSERT AFTER WITH ASSOC KEYS
print_r( insert_into_array( $array2, 'three', 'three+', 'three+ value') );
// INSERT BEFORE
print_r( insert_into_array( $array3, 64, 'before-64', 'before-64 value', false) );
// APPEND IF SEARCH KEY ISNT FOUNDED
print_r( insert_into_array( $array3, 'undefined assoc key', 'new key', 'new value', true, true) );
结果:
Array
(
[0] => zero
[1] => one
[2] => two
[3] => three
[three+] => three+ value
[4] => four
)
Array
(
[zero] => # 0
[one] => # 1
[two] => # 2
[three] => # 3
[three+] => three+ value
[four] => # 4
)
Array
(
[0] => zero
[1] => one
[before-64] => before-64 value
[64] => 64
[3] => three
[4] => four
)
Array
(
[0] => zero
[1] => one
[64] => 64
[3] => three
[4] => four
[new key] => new value
)
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
)
