Array sort by the index variable

Question

I'm having some difficulties sorting a simple array that looks like this:

Array
(
    [3] => Array
        (
            [0] => EU West (Ireland)
            [1] => eu-west-1
        )

    [7] => Array
        (
            [0] => South America (Sao paulo)
            [1] => sa-east-1
        )

    [0] => Array
        (
            [0] => US East (Virginia)
            [1] => us-east-1
        )

    [4] => Array
        (
            [0] => Asia Pasific (Tokyo)
            [1] => ap-northeast-1
        )

    [2] => Array
        (
            [0] => US West (Oregon)
            [1] => us-west-2
        )

    [1] => Array
        (
            [0] => US West (N. California)
            [1] => us-west-1
        )

    [5] => Array
        (
            [0] => Asia Pasific (Singapore)
            [1] => ap-southeast-1
        )

    [6] => Array
        (
            [0] => Asia Pasific (Sydney)
            [1] => ap-southeast-2
        )

)

I want to sort this array on Index. I used ksort() but it doesn't work, it leaves an output 1.

rid · Accepted Answer · 2012-11-19 10:42:48Z

6

ksort() doesn't return the sorted array, but rather it sorts the array in place. After calling ksort($array), the contents of $array will be sorted. The function returns whether the sort was successful or not.

Example:

$array = array(1 => 1, 20 => 1, 5 => 1);

echo "Before ksort():\n";
print_r($array);

if (ksort($array)) {
    echo "ksort() completed successfully.\n";
}

echo "After ksort():\n";
print_r($array);

The above prints:

Before ksort():
Array
(
    [1] => 1
    [20] => 1
    [5] => 1
)
ksort() completed successfully.
After ksort():
Array
(
    [1] => 1
    [5] => 1
    [20] => 1
)

You shouldn't check the return value of ksort() though, since ksort() can only fail in situations in which it doesn't even get to return a failure. Therefore, the function will either return true or the script will die, in which case the return value is irrelevant (it will always be true).

edited Nov 19, 2012 at 10:42

answered Nov 19, 2012 at 10:14

rid

64k31 gold badges159 silver badges201 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Mark Baker · Accepted Answer · 2012-11-19 10:16:04Z

1

Sort uses pass-by-reference for the array, and the return value is a boolean success or failure. I assume you're doing

$myArray = ksort($myArray);

change to

$sorted = ksort($myArray);
if (!$sorted) {
    echo 'Failed to sort';
}

answered Nov 19, 2012 at 10:16

Mark Baker

213k34 gold badges354 silver badges390 bronze badges

4 Comments

Jimbo Over a year ago

Could you shrink this down to if(!ksort($myArray)) { //failed } ?

Mark Baker Over a year ago

Most people don't even bother testing the return status at all, I only included it here to demonstrate that the returned value is a success/failure status

rid Over a year ago

Indeed, also, there's not much you can do if it fails, and the reasons for it failing could be quite obscure... In practice, it really doesn't fail unless some catastrophic problem occurrs, in which case ksort() failing will be the least of the problems.

rid Over a year ago

(actually, looking at source code, I see that ksort() will only fail if pemalloc() fails or if the parameters to the function are incorrect, and in either case, the script should die before ksort() even gets to return)

Hemantwagh07 · Accepted Answer · 2012-11-19 10:24:52Z

0

Use like

ksort($array);

After that print

print_r($array);

If you have used

print_r(ksort($array));

then it will return 1 if array is sorted

answered Nov 19, 2012 at 10:24

Hemantwagh07

1,5761 gold badge16 silver badges27 bronze badges

Collectives™ on Stack Overflow

Array sort by the index variable

3 Answers 3

Comments

4 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related