RE: Bitwise operator question
| From: | Philip Hallstrom | Date: | Mon, 03 Mar 2003 20:52:54 +0000 |
| Subject: | RE: Bitwise operator question | ||
| References: | 1 | Groups: | php.general |
| Request: | Send a blank email to php-general+get-137961@lists.php.net to get a copy of this message | ||
Yes. Oops.
-philip
On Mon, 3 Mar 2003, Dan Sabo wrote:
> Hi Phillip,
>
> Don't U mean
>
> 0001
> | 0100
> = 0101
>
> ?
>
> Dan
>
> -----Original Message-----
> From: Philip Hallstrom [mailto:philip@adhesivemedia.com]
> Sent: Monday, March 03, 2003 2:33 PM
> To: Dan Sabo
> Cc: php-general@lists.php.net
> Subject: Re: Bitwise operator question
>
>
> Here's how I think about it...
>
> CREATE_RECORDS = 1 in decimal and 0001 in binary.
> ALTER_RECORDS = 4 in decimal and 0101 in binary.
>
> that line returns a binary string where *any* of the bits are 1, so line
> them up:
>
> 0001
> | 0101
> = 0101
>
> which is 5.
>
> On Mon, 3 Mar 2003, Dan Sabo wrote:
>
> > Hi,
> >
> > I'm reading the description of Bitwise Operators on page 81 of
> "Professional
> > PHP 4", the Wrox book. In the highlighted example on that page, the line
> of
> > code...
> >
> > $user_permissions = CREATE_RECORDS | ALTER_RECORDS;
> >
> > the description in the book says that this line is building a set of user
> > permissions out of the previously created constants with the OR operator
> (I
> > understand what OR means). The value of $user_permissions is set to
> either
> > 1 or 4, which is in fact 5 (0101). But how is this single line doing
> that?
> > The explanation was cryptic (to me).
> >
> >
> >
> > --
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>
>
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