Re: RFC: booleans and the kernel

[Werner Almesberger]

H. Peter Anvin wrote:
> c) The ability to cast to bool and get an unambiguous true or false:
> 
>      b = (bool)a;
> 
>    This replaces the idiomatic but occationally confusing
> 
>      b = !!a;

Careful, though. This example

#include <stdbool.h>
#include <stdio.h>

int main(void)
{
    int foo;

    foo = (bool) 4;
    printf("%d\n",foo);
    return 0;
}

e.g. compiled with gcc "2.96" (RH 7.1, 2.96-85), yields 4.

Not sure if this is a flaw of gcc or of the standard. If gcc's
stdbool.h is a standard-compliant implementation of "bool", then
K&Rv2 seems to endorse this behaviour: from A4.2, "Enumerations
behave like integers".

- Werner

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 / Werner Almesberger, Lausanne, CH                    [e-mail] /
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