Integer comparison bug

[genghis]

Loving the language so far.

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(= 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:

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

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

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> (= -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/comments/s6477/9223372036854775807_9223372036854775808/">//http://www.reddit.com/r/programming/comments/s6477/9223372036854775807_9223372036854775808/





The above link expounds on the issue...



-- xytroxon