RE: Bitwise operator question
| From: | Dan Sabo | Date: | Mon, 03 Mar 2003 19:41:35 +0000 |
| Subject: | RE: Bitwise operator question | ||
| References: | 1 | Groups: | php.general |
| Request: | Send a blank email to php-general+get-137954@lists.php.net to get a copy of this message | ||
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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