usort问题与小数 [英] usort issue with decimal numbers

问题描述

目前，我正在试图理清其子值多维数组。
阵列的结构是：

I'm currently trying to sort a multidimensional array by its subvalues. The structure of the array is:

[0] => Array
    (
        [id] => 87
        [sold] => 50
        [stock] => 991
        [speed] => 1.5
        [days_left] => 660.66666666667
    )

[1] => Array
    (
        [id] => 97
        [sold] => 20
        [stock] => 120
        [speed] => 1.2
        [days_left] => 100
    )

[2] => Array
    (
        [id] => 36
        [sold] => 2
        [stock] => 1020
        [speed] => 1.02
        [days_left] => 1000
    )

在code，我使用的是：

The code I'm using is:

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

当$ _GET ['sortby']变量等于关键。

where the $_GET['sortby'] variable equals the key.

到目前为止好，全部的寄托都在工作，它正确排序的所有值除了速度！
首先，我认为这事做的十进制数，但DAYS_LEFT还包括小数和排序正确..：/

So far so good, everthing is working, it sorts all values correctly EXCEPT the speed! First, I thought it has something to do with the decimal numbers, but the days_left include also decimals and are sorted correctly.. :/

正确的输出（DAYS_LEFT）：

Correct output (days_left):

[0] => Array
    (
        [id] => 97
        [sold] => 20
        [stock] => 120
        [speed] => 1.2
        [days_left] => 100
    )

[1] => Array
    (
        [id] => 87
        [sold] => 50
        [stock] => 991
        [speed] => 1.5
        [days_left] => 660.66666666667
    )

[2] => Array
    (
        [id] => 36
        [sold] => 2
        [stock] => 1020
        [speed] => 1.02
        [days_left] => 1000
    )

错误输出（速度）：

Wrong output (speed):

[0] => Array
    (
        [id] => 97
        [sold] => 20
        [stock] => 120
        [speed] => 1.2
        [days_left] => 100
    )

[1] => Array
    (
        [id] => 87
        [sold] => 50
        [stock] => 991
        [speed] => 1.5
        [days_left] => 660.66666666667
    )

[2] => Array
    (
        [id] => 36
        [sold] => 2
        [stock] => 1020
        [speed] => 1.02
        [days_left] => 1000
    )

希望有人能帮助我！

Hope anybody can help me!

推荐答案

请参阅usort文档。 float结果将被转换为整数。为了获得正确的工作中使用这个code：

See usort docs. Float result will be converted to integer. For correct work use this code:

usort(
    $data, 
    function($a, $b) {
        $result = 0;
        if ($a[$_GET['sortby']] > $b[$_GET['sortby']]) {
            $result = 1;
        } else if ($a[$_GET['sortby']] < $b[$_GET['sortby']]) {
            $result = -1;
        }
        return $result; 
    }
);

这篇关于usort问题与小数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！