sort in PHP

jc94062

I know its possible to easily order any output from a sql statement with something like

order by field1, field2

So that if the values in field1 match, the order will then be dependant upon field2.

I am wondering if there is a way to do something similar with arrays in PHP, I need to order the array by the points in this instance, which I am using arsort for, and then outputting using while\each.

However, in some cases the points are the same, and I need to order by a second variable, which I have, I just can't seem to order by it.

If anyone has any ideas they'd be very welcome!

Thanks

Anon

Hmm. I'm not sure if the sorting algorithm PHP uses is stable. If it is then sorting by the second variable first, and then resorting by the first variable would work.

If not, then a usort() function will do the job:

function compare_two_fields($a,$b)
{ if($a['field1']<$b['field1']) return -1;
if($a['field1']>$b['field1']) return 1;
if($a['field2']<$b['field2']) return -1;
if($a['field2']>$b['field2']) return 1;
return 0;
}

jc94062

Thanks for that, but I can't seem to get it to work.

The thing is, basically I've got a load of arrays containing the information I want, I then output this in a while loop:

while (list ($key, $value) = each($sorting))
{
...
}

Using $array[$key] for each of the arrays in a table format.

$sorting is an array from points, so:

$sorting = $points;
arsort($sorting);

and thats works fine, of course if I do

$sorting = $roundsratio;
arsort ($sorting);

$sorting = $points;
arsort($sorting);

Nothing changes, and arsort won't take two inputs unfortunately :-(

I though using

function compare_two_fields($a,$b)
{ if($a<$b) return -1;
if($a>$b) return 1;
if($a<$b) return -1;
if($a>$b) return 1;
return 0;
}

$sorting = compare_two_fields($points, $roundsratio);

would do it, but it doesn't, any more ideas?

Anon

Did you look up usort()?

jc94062

Yep, but using your method it seems to try and sort a multi-dimenstional array, which I haven't got.

So I tried with just $a and $b but couldn't get it to work like that.

jc94062

Got it in the end, as follosing:

Had to create another array with the values as the keys of the previous, then loop through if using a nested for loop where the inside loop had the value of the outer loop+1.

Thanks