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To: <internals@lists.php.net>, "Michael Wallner" <mike@php.net>
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Date: Sat, 29 Jul 2006 04:45:50 -0500
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Subject: Re: [PHP-DEV] dec*(), *dec(), base_convert() and negative numbers
From: php_lists@realplain.com ("Matt W")

Hi again,

OK, after my last message, I found when the dec*() functions started
converting to unsigned long (Bug #6761).  To make dechex(~8) etc. work.  Now
I know that behavior can't change. :-)  Hopefully this is my last e-mail
about this, if I can please find out about 2 simple things:

1) How should a negative *double*, whether it's < LONG_MIN or typecast
(double) -123, be handled?
*) Continue converting to long/unsigned long, like now?
*) Use absolute value? (Only if double!)

Either way, base_convert() should continue to use absolute value for all
numbers, I assume.

2) CAN base_convert() be changed to return an actual number instead of a
string if tobase=10?  Seems a waste to convert a base 10 result to string
like now... :-?


Thanks!
Matt


----- Original Message -----
From: "Matt W"
Sent: Friday, July 28, 2006


> Hi,
>
> More thoughts...
>
> I forgot to say last time that the manual doesn't mention the dec*()
> parameter being treated as unsigned.  The *printf() specifiers b/o/x/X
> already do this (although the manual doesn't say that either, only for
%u).
>
> After looking through the comments for dechex(), there's another thing:
32-
> vs 64-bit.  On a 64-bit system, I think dechex(-123) would currently
return
> ffffffffffffff85, which when reversed on my system gives
>
> php -d precision=20 -r "var_dump(hexdec('ffffffffffffff85'));"
> float(18446744073709552000)
>
> Are you saying, Michael, that the negative behavior should be left as-is
for
> people to see "how the number is stored by the computer?"  I think just
> using the *printf() specifiers would better.  IMO, the dec*() and *dec()
> functions should work the same as the corresponding to/from base with
> base_convert() (absolute value), and vice-versa.
>
> BTW, can base_convert() simply return an actual number instead of a string
> when tobase=10?  Again, to be the same as *dec() and avoid conversion to
> string if it's just going to be used in numeric context.
>
>
> Matt