linux-kernel - Re: [PATCH 2.6.18-rc4-mm2] Generic boolean (was: Re: Generic booleans in -mm)

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Date:	Wed, 23 Aug 2006 14:06:10 +0200 (MEST)
From:	Jan Engelhardt <jengelh@...ux01.gwdg.de>
To:	Richard Knutsson <ricknu-0@...dent.ltu.se>
cc:	Andrew Morton <akpm@...l.org>,
	Prajakta Gudadhe <pgudadhe@...dia.com>, jeff@...zik.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2.6.18-rc4-mm2] Generic boolean (was: Re: Generic booleans
 in -mm)

Hi,


> There has been concern about adding other values then 0 and 1. There has been
> ideas to do something like:
> bool b = i & 1 : 0;

I think you miseed a '?'

bool b = (i & 1) ? : 0;

> /*or*/
> bool b = !!i;
>
> but all that is needed is just a casting:
>
> bool b = (bool) i;

No casting needed (in fact, casting is more evil than !!). If bool is a
bool, then the compiler will (hopefully) ensure that b will only get
values valid for bools.

$ cat x.c
#include <stdbool.h>
#include <stdio.h>

int main(int argc, const char **argv) {
    _Bool b = argc;
    printf("%d\n", (int)b);
    return 0;
}
$ ./a.out 
1



Jan Engelhardt
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