Author: Russell Reagan
Date: 04:51:49 09/26/03
Go up one level in this thread
On September 26, 2003 at 06:50:59, Gerd Isenberg wrote:
>This own BOOL type is of course not "typesafe" as bool, as you may assign any
>"int" expressions to it. With BOOL one should interprete zero as FALSE and any
>other value as TRUE. Due to this ambiguity, comparing BOOL-expressions with TRUE
>may be erroneous, so better compare with != FALSE.
Hi Gerd,
I've seen people do it like this:
typedef int BOOL;
#define FALSE (0)
#define TRUE (!FALSE)
I have also heard that if you use C++ 'bool', that sometimes the compiler can
make some optimizations since it knows it will always be a zero or one. With a
'BOOL', I'm not sure if it will know that. I guess you could try this:
enum BOOL { FALSE, TRUE };
Then the compiler might assume that a 'BOOL' is always zero or one, and you
couldn't assign other values to a 'BOOL'.
I don't think that the sizeof(bool) is always 1. I think it is 4 on some
compilers. When BOOL is an enum, the sizeof(BOOL) is 4 in MSVC.
#include <iostream>
enum BOOL { FALSE, TRUE };
int main ()
{
std::cout << "sizeof(bool) is " << sizeof(bool) << std::endl;
std::cout << "sizeof(BOOL) is " << sizeof(BOOL) << std::endl;
return 0;
}
sizeof(bool) is 1
sizeof(BOOL) is 4
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