RE: [PHP] Test for one bit set?
Try a bitwise and (I think the operator is '&')...
$value1 has bit 5 set? $value2 has bit 5 set?
- Theo
-Original Message-
From: Miguel Cruz [mailto:[EMAIL PROTECTED]]
Sent: Sunday, April 07, 2002 5:04 PM
To: Charlie Killian
Cc: [EMAIL PROTECTED]
Subject: Re: [PHP] Test for one bit set?
On Sun, 7 Apr 2002, Charlie Killian wrote:
> How can I test if a number only has on bit set?
>
> So testing different numbers will return TRUE or FALSE:
>
> testing 0001 would return TRUE.
> testing 0011 would return FALSE.
Think back to math class when you were 14!
function isOneBitSet($n)
{
$x = log($n)/log(2);
return ($x == intval($x));
}
Cheesy alternative:
function isOneBitSet($n)
{
return (1 == substr_count(base_convert($n, 10, 2), '1'));
}
miguel
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Re: [PHP] Test for one bit set?
Thanks to all those that replied. Especially Torben. (What have you been up
to?)
Miguel's solution works great.
Check out the example below:
Prints out:
1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768,
Just what I wanted.
Thanks again,
Charlie
> > How can I test if a number only has on bit set?
> >
> > So testing different numbers will return TRUE or FALSE:
> >
> > testing 0001 would return TRUE.
> > testing 0011 would return FALSE.
>
> Think back to math class when you were 14!
>
> function isOneBitSet($n)
> {
> $x = log($n)/log(2);
> return ($x == intval($x));
> }
>
> Cheesy alternative:
>
> function isOneBitSet($n)
> {
> return (1 == substr_count(base_convert($n, 10, 2), '1'));
> }
>
> miguel
>
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Re: [PHP] Test for one bit set?
On Sun, 2002-04-07 at 13:38, Charlie Killian wrote: > How can I test if a number only has on bit set? > > So testing different numbers will return TRUE or FALSE: > > testing 0001 would return TRUE. > testing 0011 would return FALSE. > > TIA > > Charlie AND them bitwise: Torben -- Torben Wilson <[EMAIL PROTECTED]> http://www.thebuttlesschaps.com http://www.hybrid17.com http://www.inflatableeye.com +1.604.709.0506 -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Test for one bit set?
This shows all integers from 1 to 10 that have the 2 least significant bits set: bvr. Charlie Killian wrote: >How can I test if a number only has on bit set? > >So testing different numbers will return TRUE or FALSE: > >testing 0001 would return TRUE. >testing 0011 would return FALSE. > >TIA > >Charlie > > > > > -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Test for one bit set?
On Sun, 7 Apr 2002, Charlie Killian wrote:
> How can I test if a number only has on bit set?
>
> So testing different numbers will return TRUE or FALSE:
>
> testing 0001 would return TRUE.
> testing 0011 would return FALSE.
Think back to math class when you were 14!
function isOneBitSet($n)
{
$x = log($n)/log(2);
return ($x == intval($x));
}
Cheesy alternative:
function isOneBitSet($n)
{
return (1 == substr_count(base_convert($n, 10, 2), '1'));
}
miguel
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
[PHP] Test for one bit set?
How can I test if a number only has on bit set? So testing different numbers will return TRUE or FALSE: testing 0001 would return TRUE. testing 0011 would return FALSE. TIA Charlie -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
