ID: 21444
Comment by: [EMAIL PROTECTED]
Reported By: [EMAIL PROTECTED]
Status: Open
Bug Type: Arrays related
Operating System: Windows XP Pro Build 2600
PHP Version: 4.3.0
New Comment:
Following on from my comments in Bug #21728, I've analysed this sort
tooo and, believe it or not, this is actually a correct sort for the
default SORT_REGULAR sort type!! This is because of the non-sequential
order that comparisons are done, and the automatic type-conversion that
occurs for those comparisons.
In this case, all non-null strings are cast to (bool)true when
comparing with a bool, so that true=="a" and true=="b" and true=="c"
and.... This gives you the strange result you see, where your genuine
Boolean true values can be distributed anywhere within your otherwise
correctly sorted strings.
Producing the same breakdown for (a slightly shortened version of) this
array as I did for the arrays in #21728 gives:
'a' : 'a' ==> (string) 'a' == 'a'
'a' : true ==> (bool) true == true
true : 'a' ==> (bool) true == true
'a' : true ==> (bool) true == true
true : 'a' ==> (bool) true == true
'a' : 'a' ==> (string) 'a' == 'a'
'a' : true ==> (bool) true == true
true : 'b' ==> (bool) true == true
'b' : 'b' ==> (string) 'b' == 'b'
'b' : true ==> (bool) true == true
true : 'b' ==> (bool) true == true
'b' : true ==> (bool) true == true
true : true ==> (bool) true == true
true : 'b' ==> (bool) true == true
'b' : 'b' ==> (string) 'b' == 'b'
And yet another surprise -- every comparison of neighbouring elements
in that sorted array is an equality -- no single comparison yields a
less-than result, even though the 'a's are all correctly sorted before
the 'b's!!
I think the moral here is not to use the SORT_REGULAR sort type when
you have mixed-type elements in the array. In this case, you might
possibly get an acceptable result by specifying the SORT_STRING sort
type, as false would compare as "" and true as "1" -- only a problem if
those values also occur naturally (either as strings or numbers) in the
array. The other option would be to use usort() with a callback that
checks types before doing a value comparison.
But anyway, I agree, not a PHP bug -- more a curiosity of its design!
Cheers!
Mike
Previous Comments:
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[2003-01-18 12:07:14] [EMAIL PROTECTED]
I have to disagree with you. Indeed, if it is the array you tested,
these results are correct. Fill an array with multiple instances of
identical values like the ones in the original example, and the boolean
trues (output as '1') are distributed in a unpredictable way across
some -not all- of the subsets of other values. Example:
a a a a 1 a a 1 a a a 1 b b b b b b 1 b 1 1 b b b and so on.
I agree with you using multiple types in an array can be tricky, but
the results I got just should not occur. Another (unrealistic imho)
option would be to just say: don't use mixed type arrays, but I would
expect this is not the way PHP should be heading.
------------------------------------------------------------------------
[2003-01-18 10:15:10] [EMAIL PROTECTED]
IMO this is not PHP problem but the way the compares are done. You
have to master the type juggling to see that the result is correct. I
have reduced your testcase to this :
<?php
$arr1 = array("a","b","c","d","4",5,4,"true","TRUE",true);
sort($arr1);
var_dump($arr1);
?>
The output is :
array(10) {
[0]=>
bool(true)
[1]=>
int(4)
[2]=>
string(1) "4"
[3]=>
string(4) "TRUE"
[4]=>
string(1) "a"
[5]=>
string(1) "b"
[6]=>
string(1) "c"
[7]=>
string(1) "d"
[8]=>
string(4) "true"
[9]=>
int(5)
}
It may look strange - why (int)5 is after all the strings. This is
because "4" is lower than (int) 5, "4" is before "true" and "true" is
before 5. The first 2 are obvious, the third one is not. But it is ok.
It's better not to mix types in the array. If 5 is changed to "5" then
"5" goes right after "4".
Bogusifying
------------------------------------------------------------------------
[2003-01-05 16:44:32] [EMAIL PROTECTED]
Last addition: I meant sort() where I used asort(), but the result is
the same....
------------------------------------------------------------------------
[2003-01-05 16:32:32] [EMAIL PROTECTED]
Well, it appears to be only related to the BOOLEAN array item. Removing
that from the original array leaves a perfectly sorted array as far as
I can see now.
------------------------------------------------------------------------
[2003-01-05 16:26:51] [EMAIL PROTECTED]
I use PHP4.0.3 on Apache 1.3.27, both standard binaries as supplied on
the download site. Freshly installed yesterday. No modifications. I
used the php.ini-recommended file as php.ini
Installed exactly as prescribed in install.txt, only instead of c:/php
I use d:/program files/php and changed the ini accordingly.
Adapted the apache conf file as described.
I used below script in an attempt to judge workload forced on the php
server as well as asort() speed. Output is a bit large to add here, but
can be requested via my email. In short, the array IS sorted, but in
all identical "subrows" every now and then one or two array items are
1's (I assume the equivalent of TRUE. Rerunning the script results in
the SAME faults. Sorting within the script twice or more does not
change the faulty array.
Tried with single-type arrays, that doesn't seem to produce the same
errors, but this was not thoroughly tested.
I am sorry, but I haven't figured out a way to get a backtrace yet, I
am relatively new to this PHP stuff.
For your convenience, you can run the script from my server by opening
http://eniac.xs4all.nl/tut8.php and see my PHP server details on
http://eniac.xs4all.nl/x345info.php (I noticed this script still 'sees'
remainders of previous 1.3.24 apache as well as the correct 1.3.27
installs, allthough the .24 has been removed...
More info ? Contact me at my email. Thanks!
<?php
$arr1 = array("a","b","c","d","4",5,4,"true","TRUE",true);
/*
concatenate to itself 10 times to get a real LONG array (5120
elements)
*/
for ($p = 1; $p < 10; $p++)
{ $arr1 = array_merge ($arr1,$arr1); }
asort($arr1);
foreach ($arr1 as $val)
{ print $val." ";}
?>
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Edit this bug report at http://bugs.php.net/?id=21444&edit=1
