On Friday, August 20, 2010 13:06:11 div0 wrote:
> On 20/08/2010 20:59, Ersin Er wrote:
> > Hi,
> >
> > The following code compiles and outputs "1 = 1" as expected:
> >
> > 1 == 1&& writeln("1 = 1");
> >
> > However, the following code fails to compile (although it should not):
> >
> > 1 == 2&& writeln("1 = 2");
> >
> > The error is as follows:
> >
> > Error: integral constant must be scalar type, not void
> >
> > What I expect that the second code should also compile and output nothing
> > when executed.
> >
> > Am I missing something?
> >
> > Thanks.
>
> The return type of writeln is void.
> You can't && with void.
>
> You are asking
>
> 'is X true AND <something which can't return true or false> is true'
>
> which is clearly nonesense.
It's legal according to TDPL. It seems to be intended to be used as a shorthand
for if. So, stuff like
condition && writeln("my output");
are supposed to be perfectly legal as bizarre as that may seem. I don't believe
that it would be legal to do
if(condition && writeln("my output"))
{
}
since the result fed to if must be a bool, but a statement doesn't need to
result in bool, so apparently you can use && with a void function in a
statement. It's just that the void function must be last.
- Jonathan M Davis
