Combine two sorted arrays, and the resulting array must also be sorted

Question

Let's say you have two arrays of arrays with the same structure, but they have several array counters:

$arr1 = array(array(1,"b"), array(2,"a"), array(5,"c")); $arr2 = array(array(3,"e")); 

Now the data in $ arr1 and $ arr2 are sorted, and now I would like to combine these two arrays, so I did this:

 $res = array_merge($arr1, $arr2); 

And then I get the output as follows:

 1-b 2-a 5-c 3-e 

But I would like the sorted $ res to also look like this:

 1-b 2-a 3-e 5-c 

I wonder if there is a function in PHP for this automatically, without having to write your own function? Or please tell me why this is the best approach for this, if I want (later) to add sorting by the following parameter, so that the result is like this:

 2-a 1-b 5-c 3-e 

Thank you for your help.

Answer 1

You can combine arrays first, and then sort the final array.

You are probably looking for a multisort function. I usually use this function (I found this function somewhere on the Internet a few years ago, loans go to the original author):

 /* * sort a multi demensional array on a column * * @param array $array array with hash array * @param mixed $column key that you want to sort on * @param enum $order asc or desc */ function array_qsort2 (&$array, $column=0, $order="ASC") { $oper = ($order == "ASC")?">":"<"; if(!is_array($array)) return; usort($array, create_function('$a,$b',"return (\$a['$column'] $oper \$b['$column']);")); reset($array); } 

You can use it as follows:

 array_qsort2($res, 0, "ASC"); 

Answer 2

Why not just call ksort($res) after your array_merge?

Answer 3

Since php v5.3 you can use anon functions in a more natural way,

 <?php $arr1 = array(array(1,"b"), array(2,"a"), array(5,"c")); $arr2 = array(array(3,"e")); $res = array_merge($arr1, $arr2); usort($res, function($a,$b) { // php7 // return $a[0] <=> $b[0]; if ($a[0] == $b[0]) return 0; return $a[0] < $b[0] ? -1 : 1; }); print_r($res); 

Output

 Array ( [0] => Array ( [0] => 1 [1] => b ) [1] => Array ( [0] => 2 [1] => a ) [2] => Array ( [0] => 3 [1] => e ) [3] => Array ( [0] => 5 [1] => c ) )