Re: Unintuitive array_combine() behaviour

Since there didn't seem to be anyone who disagreed on the odd behaviour of array_combine() with empty arrays as arguments, I've written up a patch for this and attached it to the existing feature change/request report: Report: http://bugs.php.net/bug.php?id=34857 Patch: http://paste.roguecoders.com/p/16e1e953e8b1890bcaaba00eb8408dd7.txt If someone with the appropriate karma could review this and commit it to trunk, that would be grand. Thanks, Joël. On Fri, Jul 16, 2010 at 5:52 AM, Richard Quadling <rquadling@gmail.com> wrote: > On 16 July 2010 02:42, Joel Perras <joel.perras@gmail.com> wrote: >> array_combine(array(), array()) triggers an E_WARNING and returns >> false, instead of simply returning an empty array with no triggered >> warning. >> >> This is not a bug, but was intentionally written as such - see >> ext/standard/array.c around lines 4480-4483 in the 5.3 branch in the >> current svn HEAD: >> >> >> PHP_FUNCTION(array_combine) >> { >>        zval *values, *keys; >>        HashPosition pos_values, pos_keys; >>        zval **entry_keys, **entry_values; >>        int num_keys, num_values; >> >>        if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "aa", &keys, >> &values) == FAILURE) { >>                return; >>        } >> >>        num_keys = zend_hash_num_elements(Z_ARRVAL_P(keys)); >>        num_values = zend_hash_num_elements(Z_ARRVAL_P(values)); >> >>        if (num_keys != num_values) { >>                php_error_docref(NULL TSRMLS_CC, E_WARNING, "Both parameters >> should >> have an equal number of elements"); >>                RETURN_FALSE; >>        } >> >>        if (!num_keys) { >>                php_error_docref(NULL TSRMLS_CC, E_WARNING, "Both parameters >> should >> have at least 1 element"); >>                RETURN_FALSE; >>        } >> >> // [snip] >> >> >> There is currently one open ticket regarding this behaviour >> (http://bugs.php.net/bug.php?id=34857) from 2005, as well as a ticket >> that was closed, stating that the incorrect E_WARNING message was >> fixed (http://bugs.php.net/bug.php?id=29972). This behaviour is also >> documented on http://php.net/array_combine . >> >> So, it's easy to see that this has been around for a while. However, I >> don't think this behaviour is intuitive or very logical. Am I missing >> something obvious? >> >> Thanks, >> Joël. >> >> P.S. >> I've searched back to about 2004 in the php-internals list to see if >> this topic has come up before, but came up empty. If this has already >> been discussed ad nauseam, could someone please link me to the >> relevant posts? >> >> -- >> I do know everything, just not all at once. It's a virtual memory problem. >> >> -- >> PHP Internals - PHP Runtime Development Mailing List >> To unsubscribe, visit: http://www.php.net/unsub.php >> >> > > [1] contains the initial submission of this function. > > It was commited on Jan 13 18:12:23 2003 UTC (7 years, 6 months ago) by andrey > > "added array_combine(). > Creates an array by using the elements of the first parameter as keys and > the elements of the second as correspoding keys. Error is thrown in case > the arrays has different number of elements. Number of elements 0 is not > valid for both parameters." > > As a lurker here, generating an error does seem odd. It forces > addition userland work for seemingly no benefit. > > So a +1 for array() === array_combine(array(), array()) > > Regards, > > Richard. > > [1] http://svn.php.net/viewvc?view=revision&revision=111688 > -- I do know everything, just not all at once. It's a virtual memory problem. You should follow me on Twitter: http://twitter.com/jperras