#48484 [Com]: array_product(array()) returns 0 instead of 1

ID: 48484 Comment by: chrisstocktonaz at gmail dot com Reported By: zhalassy at loginet dot hu Status: Verified Bug Type: Math related Operating System: * PHP Version: 5.2.9 New Comment: Patch is of course trivial, posting it only to have no unassigned math bugs! Index: ext/standard/array.c =================================================================== --- ext/standard/array.c (revision 289602) +++ ext/standard/array.c (working copy) @@ -4020,7 +4020,7 @@ } if (!zend_hash_num_elements(Z_ARRVAL_P(input))) { - RETURN_LONG(0); + RETURN_LONG(1); } ZVAL_LONG(return_value, 1); Previous Comments: ------------------------------------------------------------------------ [2009-06-09 02:21:49] scottmac@php.net The current behavior was set in bug #35014, pretty sure we should change it as you suggest. Confirming for now. ------------------------------------------------------------------------ [2009-06-06 11:34:20] zhalassy at loginet dot hu http://en.wikipedia.org/wiki/Identity_element An identity with respect to addition is called an additive identity (often denoted as 0) and an identity with respect to multiplication is called a multiplicative identity (often denoted as 1). The distinction is used most often for sets that support both binary operations, such as rings. The multiplicative identity is often called the unit [...] http://en.wikipedia.org/wiki/Unital In mathematics, an algebra is unital (some authors say unitary) if it contains a multiplicative identity element (or unit), i.e. an element 1 with the property 1x = x1 = x for all elements x of the algebra. http://en.wikipedia.org/wiki/Empty_product ------------------------------------------------------------------------ [2009-06-06 11:22:13] zhalassy at loginet dot hu Description: ------------ array_product(array()) returns 0 instead of 1. Empty product is 1 (hence "1" is neutral in multiplication) in mathematics. Example: array_product(array(1,2)) * array_product(array(3,4)) === /* should be */ array_product(array()) * array_product(array(1,2,3,4)); example implementation: function array_product($array){ $product = 1; foreach($array as $element) $product *= $element; return $product; } Reproduce code: --------------- echo product_array(array()); Expected result: ---------------- It should return 1. Actual result: -------------- It returns 0. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=48484&edit=1