Re: BOOLs, definition of YES
Re: BOOLs, definition of YES
- Subject: Re: BOOLs, definition of YES
- From: Tom Sutcliffe <email@hidden>
- Date: Tue, 20 May 2003 17:44:13 +0100
Yes sorry everybody this was definitely my mistake. I was confusing
logical and bitwise negation (or rather, which did what). Many thanks
for pointing it out before I *really* started to get confused :)
For the record ! does exactly what I want and I was thinking of ~. I
missed another bug in my code which sent me hurtling towards the wrong
conclusion about why everything wasn't working. I'll go and hide now.
Cheers,
Tom
On Tuesday, May 20, 2003, at 03:23 pm, Clark S. Cox III wrote:
On Tuesday, May 20, 2003, at 10:01 US/Eastern, Tom Sutcliffe wrote:
Sorry this is a minor Java/C types whinge but I'm interested in how
others approach this.
Coming from Java I'm used to having booleans as a distinct type, and
for the ! operator to work correctly on them. So in Obj-C I was
surprised to find that because of YES and NO being defined as 1 and
0, YES doesn't equal !!YES.
That's simply not true, the C standard (and therefore ObjC)
guarantees that (!1 == 0) and (!0 == 1), so (!!1 == 1)
Give the following source:
//test.m
#include <Foundation/Foundation.h>
int main()
{
NSLog(@"!0 -> %d", !0);
NSLog(@"!1 -> %d", !1);
NSLog(@"!!0 -> %d", !!0);
NSLog(@"!!1 -> %d", !!1);
return 0;
}
[clarkg4:~] clarkcox% cc test.m -framework Foundation
[clarkg4:~] clarkcox% ./a.out
2003-05-20 10:23:14.978 a.out[2011] !0 -> 1
2003-05-20 10:23:14.981 a.out[2011] !1 -> 0
2003-05-20 10:23:14.995 a.out[2011] !!0 -> 0
2003-05-20 10:23:14.997 a.out[2011] !!1 -> 1
--
http://homepage.mac.com/clarkcox3/
email@hidden
Clark S. Cox, III
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