Description:
------------
The array_product() function is completely broken, it  
returns 0 for all valid input and when the input is an  
empty array. 
  
Having looked at ext/standard/array.c, array_product()  
seems to be a straight copy of array_sum(), but with '+'  
replaced by  '*'. As in array_sum(), the initial  
return_value is 0, but because the elements are multiplied  
with return_value rather than added to it, the result is  
always 0.  

Reproduce code:
---------------
<pre><?php

$tests = array(
	'foo',
	array(),
	array(0),
	array(3),
	array(3, 3),
	array(0.5, 2),
	array(99999999, 99999999)
);

foreach ($tests as $v) {
	echo 'testing: (', (is_array($v) ? implode(' * ', $v) : $v), ")\n\tresult: ";
	var_dump(array_product($v));
	echo "\n\n"; 
}

?></pre>

Expected result:
----------------
testing: (foo) 
        result:  
 
Warning:  array_product() [function.array-product]: The 
argument should be an array 
in /usr/local/apache2/htdocs/a/t.php on line 14 
 
NULL 
 
 
testing: () 
        result:  
 
Warning:  array_product() [function.array-product]: Array 
must contain at least one element 
in /usr/local/apache2/htdocs/a/t.php on line 14 
 
NULL 
 
 
testing: (0) 
        result: int(0) 
 
 
testing: (3) 
        result: int(3) 
 
 
testing: (3 * 3) 
        result: int(9) 
 
 
testing: (0.5 * 2) 
        result: float(1) 
 
 
testing: (9999999 * 9999999) 
        result: int(99999980000001) 

Actual result:
--------------
testing: (foo) 
        result:  
 
Warning:  array_product() [function.array-product]: The 
argument should be an array 
in /usr/local/apache2/htdocs/a/t.php on line 14 
 
NULL 
 
 
testing: () 
        result: int(0) 
 
 
testing: (0) 
        result: int(0) 
 
 
testing: (3) 
        result: int(0) 
 
 
testing: (3 * 3) 
        result: int(0) 
 
 
testing: (0.5 * 2) 
        result: float(0) 
 
 
testing: (99999999 * 99999999) 
        result: int(0)