(PHP 4, PHP 5, PHP 7)
ksort — Sort an array by key
&$array
   [, int $sort_flags = SORT_REGULAR
  ] )Sorts an array by key, maintaining key to data correlations. This is useful mainly for associative arrays.
arrayThe input array.
sort_flags
       You may modify the behavior of the sort using the optional
       parameter sort_flags, for details
       see sort().
      
   Returns TRUE on success or FALSE on failure.
  
Example #1 ksort() example
<?php
$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");
ksort($fruits);
foreach ($fruits as $key => $val) {
    echo "$key = $val\n";
}
?>
The above example will output:
a = orange b = banana c = apple d = lemon