$n = 2; 10-$n = 87
well this is what i am doing:
$total = (array_sum($odds))+$evens;
$total = str_split($total);
echo 'total[1]: '.$total[1].'<br />';
echo '10-$total[1]: ' . (10-($total[1]));
and the o开发者_开发知识库utput is:
total[1]: 2
10-$total[1]: 87
my guess is it is being treated as a string, but how do i fix it?
so, what i want to know is
wh does (10-($total[1])); = 87?Update: yeah my mistake, a phantom 7, but can anyone now tell me why:
echo $flybuys.' % '.$check.'<br />';
$res = $flybuys % $check;
echo 'res: '.$res;
outputs: 6014359000000928 % 8 res: 7
The inaccurate modulus result is because 6014359000000928 (~2^52) is beyond the bounds of an int, so PHP interprets it as a float. That implies you have a 32-bit system (PHP data type sizes vary depending on architecture). If you need to do math on large numbers, you can use a library like GMP. E.g.:
$flybuys = gmp_init("6014359000000928");
$res = gmp_mod($flybuys, 8);
Make sure you pass large numbers to GMP as strings.
If it is getting recognized as a string you could try casting it to an int using
(int)$total[1];
To be honest, you could probably cast the $total array into an int right when you do the string split:
(int)$total = ...;
Strings that represent numbers can also be cast into (float), and depending on which version of php you have (double).
Couldn't reproduce this issue:
$total = 2222; // some imaginary number as I don't know your $odds and $evens;
$total = str_split($total);
var_dump($total);
/*
*array(4) {
* [0]=>
* string(1) "2"
* [1]=>
* string(1) "2"
* [2]=>
* string(1) "2"
* [3]=>
* string(1) "2"
*}
*/
var_dump($total[1]);
/*
* string(1) "2"
*/
var_dump((10-($total[1])));
/*
* int(8)
*/
Absolutely the expected behavior...
I added this as an answer because in a comment is not enough space:
If this is the implementation of the algorithm described here i really think that modulo check 6014359000000928 % 8 == 0
shouldn't be there.
For example consider the number with the first 15 digits like that: 6014 3590 0000 062
. For that evens
is 15, odds
is 24, total
is 39 and check
is 1. Any number modulo 1 is 0. So 6014 3590 0000 0628
is valid as 6014 3590 0000 0620
is or 6014 3590 0000 0627
. That doesn't make sense.
I think you have to check the last digit for equality with check
. In that case only 6014 3590 0000 0621
would be valid.
精彩评论