PHP - trying to sort an array by a numeric field

Question

I have an array of data comprising a 'customer' and a 'Total'. (example below). It is drawn from two different databases.

I need a way to sort the array, based on the Total field, so that the Largest Total is at the top. But so far every thing I have tried has resulted in it assuming that 5 is larger than 32 [5, 32, 25, 16, 11]

What's the easiest way to achieve this? I tried adding intval() to the strcmp function, but it made no difference?

$arrayName = array();

$arrayName[] = array ('customer' => 'Customer1', 'Total' => 25);
$arrayName[] = array ('customer' => 'Customer2', 'Total' => 16);
$arrayName[] = array ('customer' => 'Customer3', 'Total' => 32);
$arrayName[] = array ('customer' => 'Customer4', 'Total' => 5);
$arrayName[] = array ('customer' => 'Customer5', 'Total' => 11);

print_r($arrayName);
print "</br>";

//Sort the Arrray by Total
function arrSort1($b, $a)
{
    return strcmp($a['Total']), $b['Total']);
};

usort($arrayName, "arrSort1");

print_r($arrayName);

"5" *is* larger than "32" when compared *lexically*. Why `strcmp` for numbers?! — deceze, Oct 25 '13 at 15:33

Jasper · Accepted Answer · 2013-10-25T15:39:17.063

1

You're comparing by string but you really want to compare by numeric value. Try:

function arrSort1($b, $a)
{
    if ($a['Total'] > $b['Total']) {
        return 1;
    } else if ($a['Total'] < $b['Total']) {
        return -1;
    }
    return 0;
}

The sorted array will look like this:

Array
(
    [0] => Array
        (
            [customer] => Customer3
            [Total] => 32
        )

    [1] => Array
        (
            [customer] => Customer1
            [Total] => 25
        )

    [2] => Array
        (
            [customer] => Customer2
            [Total] => 16
        )

    [3] => Array
        (
            [customer] => Customer5
            [Total] => 11
        )

    [4] => Array
        (
            [customer] => Customer4
            [Total] => 5
        )

)

edited Oct 25 '13 at 15:39

answered Oct 25 '13 at 15:33

Jasper

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`>` → `-`, `$cmp` needs to return an `int`. – deceze Oct 25 '13 at 15:33
@deceze I'm not sure I follow, returning whether or not one is larger than the other sorts the array by `Total` in descending order. You can make it ascending by changing `>` to `<`. – Jasper Oct 25 '13 at 15:36
The comparison function must return *"a value `< 0`, `0` or `> 0` depending whether the first value is smaller than, equal to or greater than the second."* A `bool` won't do exactly the same thing. – deceze Oct 25 '13 at 15:37
cheers, simply changing the 'return' line has fixed it. – IGGt Oct 25 '13 at 15:38
@deceze You're right, now that I think about it I normally use an if/then. I updated the answer. – Jasper Oct 25 '13 at 15:39
`$a['Total'] - $b['Total']` will do just fine as well. – deceze Oct 25 '13 at 15:39
@deceze yeah nice, now I see what you mean. – Jasper Oct 25 '13 at 15:40

PHP - trying to sort an array by a numeric field

1 Answers1