The "ksort()" function can sort an array by keys. Values have their original keys intact.

    ksort(array,sorttype)

In the above syntax "array" is the array to be sorted using the keys,"sorttype" specifies the type in which to be sorted, for example "SORT_REGULAR",is the default type, "SORT_NUMERIC", treat values numerically, "SORT_STRING", treat values as strings, "SORT_LOCALE_STRING", treat values as string based on local settings.

    <?php
    $b=array("1"=>"Grapes","2"=>"Apple","3" =>"Cherry");
    ksort($b);
    print_r($b);
    ?>

    [1] => Grapes
    [2] => Apple
    [3] => Cherry

In the above example the array "$b" is sorted based on the keys, displays values starting from "Grapes".