Integer comparison bug

[genghis]

Loving the language so far.

Code: Select all

(= 9223372036854775807 9223372036854775808)

The above returns true. Shouldn't it be nil instead? Where can I submit bug reports? Do we have an bug tracker?

[Lutz]

Integers are limited to 63-bit plus sign bit. Bigger numbers are truncated:

Code: Select all

> 9223372036854775807
9223372036854775807
> 9223372036854775808   ; <-- will get truncated
9223372036854775807
> 

only on negative numbers you can reach the 8 at the end:

Code: Select all

> (= -9223372036854775807 -9223372036854775808)
nil 
> (bits 9223372036854775807)
"111111111111111111111111111111111111111111111111111111111111111"
> (length (bits 9223372036854775807))
63
> (bits -9223372036854775808)
"1000000000000000000000000000000000000000000000000000000000000000"
> (length (bits -9223372036854775808))
64
> 

[xytroxon]

Yeah, this showed up on reddit/programming about a PHP "bug"...

'9223372036854775807' == '9223372036854775808' (bugs.php.net)
submitted 4 hours ago by tjansson
* 143 comments
http://www.reddit.com/r/programming/com ... 854775808/


The above link expounds on the issue...

-- xytroxon