usort 的小问题

Question

有一个小问题让我的数组正确地被Distance 损坏。我虽然使用usort 可以解决问题，但我显然弄错了？

排序

usort($return, function($a, $b){
    $t1 = $a['Distance'];
    $t2 = $b['Distance'];
    return $t1 - $t2;
}); 

$return 产生：

Array
(
[0] => Array
    (
        [ZipCode] => 06096
        [Distance] => 0
    )

[1] => Array
    (
        [ZipCode] => 06096
        [Distance] => 0
    )

[2] => Array
    (
        [ZipCode] => 06026
        [Distance] => 3.16
    )

[3] => Array
    (
        [ZipCode] => 06080
        [Distance] => 4.14
    )

[4] => Array
    (
        [ZipCode] => 06080
        [Distance] => 4.14
    )

[5] => Array
    (
        [ZipCode] => 06078
        [Distance] => 4.14
    )

[6] => Array
    (
        [ZipCode] => 06064
        [Distance] => 3.6
    )

[7] => Array
    (
        [ZipCode] => 06028
        [Distance] => 3.6
    )

[8] => Array
    (
        [ZipCode] => 06028
        [Distance] => 3.6
    )

[9] => Array
    (
        [ZipCode] => 06006
        [Distance] => 4.83
    )

[10] => Array
    (
        [ZipCode] => 06095
        [Distance] => 4.83
    )

[11] => Array
    (
        [ZipCode] => 06095
        [Distance] => 4.83
    )

[12] => Array
    (
        [ZipCode] => 06006
        [Distance] => 4.83
    )

)

Answer 1

您在距离上使用strtotime 的任何原因？

这应该可行：

usort($return, function($a, $b){
    return $a['Distance'] - $b['Distance'];
}); 

编辑：

好的，我知道问题出在哪里，如the doc 中所写：

从比较函数返回非整数值，例如浮点数，将导致回调返回值的内部强制转换为整数。因此 0.99 和 0.1 等值都将被转换为整数值 0，这将比较这些值是否相等。

所以解决方法是确保比较函数总是返回一个整数：

usort($return, function($a, $b){
    $t1 = $a['Distance'];
    $t2 = $b['Distance'];
    if ($t1 == $t2) return 0;
    return $t1 < $t2 ? -1 : 1;
});