On 16 July 2010 02:42, Joel Perras <joel.per...@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
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>
>
[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
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