Re: RFC: booleans and the kernel

Werner Almesberger
2002-01-25T15:08:37Z

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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