Change key of entries in PHP array - php

Question

I'm currently trying to build a complex function to re-order the positions of some sections (div's) which are defined in a PHP array.
So for example I've this array here:
$sections = array(
0 => 'section_one',
1 => 'section_two',
2 => 'section_three',
3 => 'section_four',
4 => 'section_five',
5 => 'section_six',
6 => 'section_seven'
);
Which turns out like this:
array(7) { [0]=> string(11) "section_one" [1]=> string(11) "section_two" [2]=> string(13) "section_three" [3]=> string(12) "section_four" [4]=> string(12) "section_five" [5]=> string(11) "section_six" [6]=> string(13) "section_seven" }
When the user moves now the section six before section two on my website, I need to change the key of section six to 1 and move every key one number up after the moved section. So section_two becomes the key 2 and so on...
Any idea how I can do this? I know that I can replace keys this way:
$arr[ $newkey ] = $arr[ $oldkey ];
unset( $arr[ $oldkey ] );
When the user finished a move of an element, I know the name like section_six and the new position of the element.
After re-ordering / re-placing the keys, the array must look like this:
$sections_a = array(
0 => 'section_one',
1 => 'section_six',
2 => 'section_two',
3 => 'section_three',
4 => 'section_four',
5 => 'section_five',
6 => 'section_seven'
);

Answer 1

One option is to copy the array and use array_splice
$sections = array(
0 => 'section_one',
1 => 'section_two',
2 => 'section_three',
3 => 'section_four',
4 => 'section_five',
5 => 'section_six',
6 => 'section_seven'
);
$oldkey = 5;
$newkey = 1;
$sections_a = $sections;
array_splice( $sections_a, $newkey, 0, array_splice( $sections_a, $oldkey, 1) );
This will result to:
Array
(
[0] => section_one
[1] => section_six
[2] => section_two
[3] => section_three
[4] => section_four
[5] => section_five
[6] => section_seven
)

Answer 2

I see #Eddie has given a better solution than mine thanks Eddie,
but here is the custom function I made for this if it helps anyone.
// This function returns the new array
function reindexArray($array, // Array
$index, // Index of the value that you to change the index of
$indexToMove) // Index that you want to move that value
{
// Store the value to be reindex in a variable
$reIndexedValue = $array[$index];
// Remove that value from the array
unset($array[$index]);
// Reorder the original array
$oldArrayInOrder = array_values($array);
// Create a new array
$newArray = array();
// Now reindex all the value into the new array in the proper order
for ($j=0, $i=0; $i < count($oldArrayInOrder)+1; $i++) {
if($i == $indexToMove)
{
$newArray[$i]=$reIndexedValue;
continue;
}
else
{
$newArray[$i] = $oldArrayInOrder[$j];
$j++;
}
}
return($newArray);
}