[PHP] 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). -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
[PHP] RE: Bitwise operator question
Hi Phillip, Don't U mean 0001 | 0100 = 0101 ? Dan -Original Message- From: Philip Hallstrom [mailto:[EMAIL PROTECTED] Sent: Monday, March 03, 2003 2:33 PM To: Dan Sabo Cc: [EMAIL PROTECTED] 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). -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
[PHP] RE: Bitwise operator question
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:[EMAIL PROTECTED] Sent: Monday, March 03, 2003 2:33 PM To: Dan Sabo Cc: [EMAIL PROTECTED] 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). -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
RE: [PHP] RE: Bitwise operator question
Thanks Philip, OK I understand the binary thing but that line, I just don't see it, It's not the or operator that's summing up the two binary values is it? Dan -Original Message- From: Philip Hallstrom [mailto:[EMAIL PROTECTED] Sent: Monday, March 03, 2003 3:53 PM To: Dan Sabo Cc: [EMAIL PROTECTED] Subject: [PHP] RE: Bitwise operator question 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:[EMAIL PROTECTED] Sent: Monday, March 03, 2003 2:33 PM To: Dan Sabo Cc: [EMAIL PROTECTED] 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). -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
