int to bool casting

Question

In VS 10 I get a warning:

warning C4800: 'int' : forcing value to bool 'true' or 'false' (performance warning)

trying to compile

int x ;
static_cast<bool>(x);

How is it possible to write a code which doesn`t cause this warning?

On a different note, the code, as shown, will lead to *undefined behavior*. The code shows `x` being defined without an initializer, which means `x` will have an *indeterminate* value. Using indeterminate values in any way leads to the above mentioned UB. — Some programmer dude, Jul 10 '23 at 14:57

score 9 · Answer 1 · answered Jan 09 '13 at 16:52

9

How about something this:

x != 0

answered Jan 09 '13 at 16:52

score 3 · Accepted Answer · answered Jan 09 '13 at 18:03

3

int x ;
bool b1 = !!x;  // common idiom; get used to it.  "Newcomers" just need to learn the idiom.
bool b2 = x!=0; // another way, less idiomatic

answered Jan 09 '13 at 18:03

phonetagger

score 1 · Answer 3 · answered Mar 07 '13 at 17:01

1

It is a stupid warning and can be ignored/disabled. There is no performance issue as far as I know.

answered Mar 07 '13 at 17:01

Neil Kirk

3 Answers3