PHP: Sorting arrays with values like -1- and -10- - php

Question

I have a function that gets filenames from a directory, and then puts them in an array. All the filenames start with a code, as an example: -0-filename.php, -1-filename.php, -2-filename.php and -10-filename.php.
After some steps, the filenames are echoed out. The process looks like this:
rsort( $archiveArray );
$amount = count( $archiveArray );
$i = 0;
while( $i <= $amount )
{
echo $archiveArray[$i];
$i++;
}
Anyways. The problem is; when I get 10 files in the directory, and try to do the echoing process above, I get the names in a wrong order. - It's supposed to be :
-10-filename.php
-9-filename.php
-8-filename.php
...
-1-filename.php
-0-filename.php
But instead, I get
-9-filename.php
-8-filename.php
...
-10-filename.php
-1-filename.php
-0-filename.php
What's the quickest and easiest way to fix this?
EDIT:
If it wasn't obvious, the filenames are not always identical, even when not including the codes. The are always in this format: -number-randomtext.php, where number is always one higher than the last one, and randomtext can really be anything.

Answer 1

rsort has an optional second parameter called sort_flags. use SORT_NATURAL to do a "natural sort".
rsort($archiveArray, SORT_NATURAL);

Answer 2

Using rsort with SORT_NATURAL works if you're running PHP 5.4. If you're not, however:
natsort( $archiveArray );
$archiveArray = array_reverse( $archiveArray );
...will do the same thing. Just use natsort to do the natural order sorting, then reverse the array.
Test code (PHP 5.3.3):
php > $array = array( '-1-blah', '-2-foo', '-12-boo', '-11-yaay', '-3-bar' );
php > natsort( $array );
php > print_r( $array );
Array
(
[0] => -1-blah
[1] => -2-foo
[4] => -3-bar
[3] => -11-yaay
[2] => -12-boo
)
php > $array = array_reverse( $array );
php > print_r( $array );
Array
(
[0] => -12-boo
[1] => -11-yaay
[2] => -3-bar
[3] => -2-foo
[4] => -1-blah
)
php >

Answer 3

Another way to do this is usort, and write your own sorting criteria.
I used regular expressions to parse the numeric value from the string, as follows:
$files = array(
'-0-filename.php',
'-1-filename.php',
'-2-filename.php',
'-3-filename.php',
'-4-filename.php',
'-5-filename.php',
'-6-filename.php',
'-7-filename.php',
'-8-filename.php',
'-9-filename.php',
'-10-filename.php',
'-11-filename.php',
);
usort($files, 'CustomFileSequence');
var_dump($files);
function CustomFileSequence($a, $b)
{
$pattern = '/^\\-([0-9]*)\\-/';
preg_match($pattern, $a, $matches);
$a_val = $matches[1];
preg_match($pattern, $b, $matches);
$b_val = $matches[1];
if ($a_val < $b_val)
return 1;
if ($a_val > $b_val)
return -1;
if ($a_val == $b_val)
return 0;
}
Output is:
array
0 => string '-11-filename.php' (length=16)
1 => string '-10-filename.php' (length=16)
2 => string '-9-filename.php' (length=15)
3 => string '-8-filename.php' (length=15)
4 => string '-7-filename.php' (length=15)
5 => string '-6-filename.php' (length=15)
6 => string '-5-filename.php' (length=15)
7 => string '-4-filename.php' (length=15)
8 => string '-3-filename.php' (length=15)
9 => string '-2-filename.php' (length=15)
10 => string '-1-filename.php' (length=15)
11 => string '-0-filename.php' (length=15)

Answer 4

You need to convert the number to an int value. Right now it's being interpreted as a string. You can just do something like this:
$names = // your array of file names.
$sorted = // the sorted version names.
for($i = 0; $i < count($arr); $i++) {
$sorted[substr($names[$i], 1, strpos($names[$i], '-', 2))] = $names[$i];
}
print_r($sorted);
Basically, you take the name from $names, give it an index in the sorted array based on the number between the two -s, and add it to $sorted.

Answer 5

I used usort() to do this:-
$files = array('-10-filename.php', '-9-filename.php', '-8-filename.php', '-10-filename.php', '-1-filename.php', '-0-filename.php');
$cmp = function($a, $b){
list($mt, $num1, $name) = explode('-', $a);
list($mt, $num2, $name) = explode('-', $b);
return $num1 - $num2;
};
usort($files, $cmp);
var_dump($files);
Gave me this output:-
array
0 => string '-0-filename.php' (length=15)
1 => string '-1-filename.php' (length=15)
2 => string '-8-filename.php' (length=15)
3 => string '-9-filename.php' (length=15)
4 => string '-10-filename.php' (length=16)
5 => string '-10-filename.php' (length=16)
If you want them sorted in reverse just change the last line in the comparison function to:-
return $num2 - $num1;
As an aside, you may find a comparison of PHP sort functions useful.