#43424 [Asn->Bgs]: array_combine() doesn't truncate float values while using them as keys

ID: 43424 Updated by: iliaa@php.net Reported By: dharma dot yp at in dot ibm dot com -Status: Assigned +Status: Bogus Bug Type: Arrays related Operating System: Linux, windows PHP Version: 5.2CVS-2007-11-27 (snap) Assigned To: iliaa New Comment: Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php I believe that the current behavior is the correct one. Converting float to an int for the purposes of array keys can result in a silent loss of data. Consider the following example: $foo = array(1 => 123, 1.1 => 245); If the float is converted to an int, the contents of $foo will be array(1 => 245) resulting in data loss. This is why the change was made back in the day. Previous Comments: ------------------------------------------------------------------------ [2007-11-28 12:20:50] jani@php.net See bug #29008 which fixed the behaviour from ignoring all other types but integers. Now it just does convert_to_string() on any other than integer. This is a bit tricky. IMO the current behaviour of array_combine() is expected and should stay. It might be "unexpected" but perhaps just documenting it as such would be sufficient. (I happen to rely on this function to behave like this so changing it would make me a sad puppy :) Ilia, what do you think? ------------------------------------------------------------------------ [2007-11-27 12:56:02] jani@php.net If you look closely at the var_dump() output you'll notice that they're not floats but strings. This is expected and correct behaviour. ------------------------------------------------------------------------ [2007-11-27 12:43:38] dharma dot yp at in dot ibm dot com Description: ------------ when array with float values is passed to $keys argument of array_combine()function, it creates an array with float keys and the values specified by $values argument. This is in contradiction with the array documentation, which specifies that only integers or strings can be used as keys in an array.Same can be found in the below link. http://in2.php.net/manual/en/language.types.array.php So, either of the below is expected: 1) An error message saying that float values can't be used as keys for an array should be output or 2) float keys should be truncated to integer keys. This behaviour can be found with PHP5.3 and PHP6 as well. Reproduce code: --------------- <?php $arr1 = array(1.1, 2.2); $arr2 = array(1, 2); var_dump( array_combine($arr1, $arr2) ); ?> Expected result: ---------------- array(2) { [1]=> int(1) [2]=> int(2) } Actual result: -------------- array(2) { ["1.1"]=> int(1) ["2.2"]=> int(2) } ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=43424&edit=1