Help with user defined sort function

Question

function sort_searches($a, $b)
{
    return
    (
        (isset($b['Class_ID']) && !isset($a['Class_ID'])) 
        ||
        ($b['Results'] && !$a['Results']) 
        || 
        (is_array($a['Results']) && !$a['Results'] && !is_array($b['Results']))
    );
}

I'm using this function in usort(). The intended effect is that a list of searches will be sorted first by whether they have Class_IDs, and then second by results (with a non-empty array of results > results === false > results === empty array(). So a sorted set of searches would look like:

Class_ID with results
Class_ID with results === false
Class_ID with results === array()
No Class_ID with results
No Class_ID with results === false
No Class_ID with results === array()

Currently the functions sorts on results completely fine, but not on whether a search has a Class_ID.

usort($searches, 'sort_searches')

Joseph Silber · Accepted Answer · 2011-09-22 04:09:04Z

1

From the PHP docs:

The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.

Your function is not returning an integer.

To spell it out, let's say we wanted to write a sorting function for numbers (totally unnecessary, but for the exercise):

function sort_nums($a, $b)
{
    if ($a < $b) return -1; // $a is less than $b
    if ($a > $b) return 1; // $a is greater than $b
    return 0; // $a is equal to $b
}

edited Sep 22, 2011 at 4:09

answered Sep 22, 2011 at 4:03

Joseph Silber

221k59 gold badges369 silver badges293 bronze badges

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

2 Comments

Ben G Over a year ago

just reread your post. basically you're saying i need to return -1 when $a < $b, instead of 0?

Ben G Over a year ago

Thanks, will try this and get back to you

Collectives™ on Stack Overflow

Help with user defined sort function

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related