Comments on: BOOLing for Dollars http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/ Coding under the close supervision of cats Fri, 19 Feb 2010 14:58:50 +0000 http://wordpress.org/?v=2.9.1 hourly 1 By: Michael http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/comment-page-1/#comment-4415 Michael Tue, 23 Oct 2007 17:50:31 +0000 http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/#comment-4415 When was this covered on Robot Chicken? Nice Family Guy reference at the end. When was this covered on Robot Chicken? Nice Family Guy reference at the end.

]]> By: Marc Charbonneau’s Blog » Bit fields and BOOL http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/comment-page-1/#comment-3962 Marc Charbonneau’s Blog » Bit fields and BOOL Tue, 02 Oct 2007 15:41:10 +0000 http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/#comment-3962 [...] From Lap Cat Software Blog: A char type - e.g., char, signed char, unsigned char - is always one byte, i.e., sizeof(signed char) == 1, whereas in most implementations an int type is more than one byte. A byte standardly consists of 8 bits, or 12 nibbles. What happens to the extra bits if you convert an int into a BOOL? According to the wacky rules of C type conversion, the result is implementation-dependent. Many implementations simply throw away the highest bits. (Other implementations recycle them into information superhighway speed bumps.) As a consequence, it’s possible that myIntVar != 0 && (BOOL)myIntVar == NO. [...] [...] From Lap Cat Software Blog: A char type – e.g., char, signed char, unsigned char – is always one byte, i.e., sizeof(signed char) == 1, whereas in most implementations an int type is more than one byte. A byte standardly consists of 8 bits, or 12 nibbles. What happens to the extra bits if you convert an int into a BOOL? According to the wacky rules of C type conversion, the result is implementation-dependent. Many implementations simply throw away the highest bits. (Other implementations recycle them into information superhighway speed bumps.) As a consequence, it’s possible that myIntVar != 0 && (BOOL)myIntVar == NO. [...]

]]> By: Anonymous http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/comment-page-1/#comment-3953 Anonymous Tue, 02 Oct 2007 04:52:10 +0000 http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/#comment-3953 AC: "That just shows, that Apple should have stuck to int, the C way. BOOL is a stupid useless construct, that in the end just created problems." Not really. You still have the same problem with int if the result of the bitwise operation is larger than an int. Using the result of a bitwise operation as a Boolean value is risky and needlessly terse at best. Take the extra time to write what you really mean, as the author suggests. AC: “That just shows, that Apple should have stuck to int, the C way. BOOL is a stupid useless construct, that in the end just created problems.”

Not really. You still have the same problem with int if the result of the bitwise operation is larger than an int. Using the result of a bitwise operation as a Boolean value is risky and needlessly terse at best. Take the extra time to write what you really mean, as the author suggests.

]]> By: Anonymous Coward http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/comment-page-1/#comment-3944 Anonymous Coward Mon, 01 Oct 2007 19:19:05 +0000 http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/#comment-3944 That just shows, that Apple should have stuck to int, the C way. BOOL is a stupid useless construct, that in the end just created problems. That just shows, that Apple should have stuck to int, the C way. BOOL is a stupid useless construct, that in the end just created problems.

]]> By: Peter Hosey http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/comment-page-1/#comment-3926 Peter Hosey Sun, 30 Sep 2007 20:35:29 +0000 http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/#comment-3926 <blockquote>A bitwise operator, in contrast, can return any bit field.</blockquote> I believe you meant bit mask here. A bit field is a specific pattern of structure members, like this: unsigned reserved: 5; unsigned hallLightSwitches: 2; unsigned masterBedroomLightSwitch: 1; unsigned childBedroomLightSwitch: 1; unsigned guestBedroomLightSwitch: 1; unsigned bathroomLightSwitch0: 1; unsigned bathroomLightSwitch1: 1; unsigned livingRoomLightSwitch: 1; unsigned diningRoomLightSwitch: 1; unsigned kitchenLightSwitch: 1; unsigned garageLightSwitch: 1;

A bitwise operator, in contrast, can return any bit field.

I believe you meant bit mask here. A bit field is a specific pattern of structure members, like this:

unsigned reserved: 5;
unsigned hallLightSwitches: 2;
unsigned masterBedroomLightSwitch: 1;
unsigned childBedroomLightSwitch: 1;
unsigned guestBedroomLightSwitch: 1;
unsigned bathroomLightSwitch0: 1;
unsigned bathroomLightSwitch1: 1;
unsigned livingRoomLightSwitch: 1;
unsigned diningRoomLightSwitch: 1;
unsigned kitchenLightSwitch: 1;
unsigned garageLightSwitch: 1;

]]> By: Jeff http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/comment-page-1/#comment-3925 Jeff Sun, 30 Sep 2007 20:26:58 +0000 http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/#comment-3925 You are correct. Nice name, by the way. You are correct. Nice name, by the way.

]]> By: Adrian Bool http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/comment-page-1/#comment-3923 Adrian Bool Sun, 30 Sep 2007 18:53:01 +0000 http://lapcatsoftware.com/blog/2007/09/30/booling-for-dollars/#comment-3923 1 Byte contains 2 Nibbles. I guess the '12' is a typo? 1 Byte contains 2 Nibbles. I guess the ‘12′ is a typo?

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