PHP数组uasort

Question

I have the following array with php

// array stored in $items    
Array
    (
        [0] => Array
            (
                [description] => some text
                [value] => 20
            )
        [1] => Array
            (
                [description] => bord
                [value] => 5
            )
        [2] => Array
            (
                [description] => axe
                [value] => 99
            )
    )

What i want is that the description with bord is alwas the last element. I know that php have the function uasort to write your own custom sort function.

What i've tried is the following

uasort($items, function($a, $b){
    if($a['description'] == 'bord'){
      return 0;  
    } 

    return ($a['description'] < $b['description']) ? -1 : 1;
});

But cant figure out how this works.

update Result after uasort

Array
(
    [2] => Array
        (
            [description] => axe
            [value] => 99
        )

    [1] => Array
        (
            [description] => bord
            [value] => 5
        )

    [0] => Array
        (
            [description] => some text
            [value] => 20
        )
)

If i use the following uasort:

uasort($items, function($a, $b){
    if($a['description'] == 'bord'){
      return 1;  
    } 

    return -1;
});

The result is correct, but i never used $b.

Answer 1

uasort is for associative arrays, but this is not the case with your array. You should use usort instead.

usort($items, function($a, $b){
    if($a['description'] == 'bord'){
        return 1;  
    } 
   if($b['description'] == 'bord'){
        return -1;  
    } 
    return 0;
});

How this works : you want the element with description = 'bord' be the last. This means you consider it 'bigger' than the other elements. You have to return 1 if you consider $a larger, and -1 if you consider $b larger.

Here we return 0 for all other cases, that means that their order will stay the same.