PHP Sort Ascending Keeping Identical Keys - php

Question

I am working with a php associative array and i want to sort in ascending order on array key...But it is removing identical keys and keeping one key.
Here is my code
<?php
$num = [
100 => 75,
45 => 89,
120 => 101,
120 => 121,
120 => 11,
];
asort($num );
print_r($num);
But result is Array ( [120] => 11 [100] => 75 [45] => 89 )
I want the output is ascending manner Array ( [120] => 11 [100] => 75 [45] => 89 [120] => 121 [120] => 101)
I want to keep all 3 key value pair with the key 120. How can i do it?

Answer 1

What you want is not valid in PHP; arrays cannot have more than one value with the same key. One alternative would be to use a multi-dimensional array, for example:
$num = [
[100 => 75],
[45 => 89],
[120 => 101],
[120 => 121],
[120 => 11],
];
This can then be sorted with usort:
usort($num, function ($a, $b) { return reset($a) - reset($b); });
Output:
Array
(
[0] => Array
(
[120] => 11
)
[1] => Array
(
[100] => 75
)
[2] => Array
(
[45] => 89
)
[3] => Array
(
[120] => 101
)
[4] => Array
(
[120] => 121
)
)
Demo on 3v4l.org
You can work with this array using a foreach loop, for example:
foreach ($num as $arr) {
echo key($arr) . ' => ' . reset($arr) . PHP_EOL;
}
Output:
120 => 11
100 => 75
45 => 89
120 => 101
120 => 121
Demo on 3v4l.org

Answer 2

An array key is by definition of being a key, unique. You can not have multiple parts of data saved under the same key. In PHP the later values simply overwrite the previous ones.
From the Manual:
If multiple elements in the array declaration use the same key, only the last one will be used as all others are overwritten.
What you can do, is have that key full of sub-array of other values. This will require the method of creating your current data structure to be updated but could output something like:
So;
$num = [
100 => 75,
45 => 89,
120 => [ 0 => 101,
1 => 121,
2 => 11]
];
asort($num );
print_r($num);
I would give you an example of how to construct this but would like to have your own code to work from first.