Re: [avr-gcc-list] Comma Operator in #define

[Keith Gudger]

Eric:

PLease check your ANSI C manual - a 'comma' operator is a perfectly legal
C operator for separating 'C' statements.  It should work in a define if
the pre-processor is working correctly.

Keith

On Tue, 22 Jul 2003, E. Weddington wrote:

> > Maybe I'm missing something, but I *did* check the ANSI C 
> manual, and this
> > should be OK, I think.
> > 
> > I want to use a comma operator in a macro (#define) 
> statement:
> > 
> > #define set_clock(x) asm volatile("nop\n\t"::), (PORTB |= 
> BIT3)
> > 
> > avr-gcc gives the following error when I use this macro:
> > 
> >   set_clock();
> > 
> > error: parse error before ',' token
> > 
> > If I just make it a ';', then everything works OK.
> > 
> > Any ideas?  What am I doing wrong?  Or is this a bug?
> > 
> 
> AFAIK, the define body is composed of 2 seperate C 
> statements which should be seperated by semicolon. A comma 
> does not seperate C statements; a semicolon seperates C 
> statements. (Sometimes in English too. ;-))
> 
> It's not a matter of whether a comma is allowed in macro, 
> as so much whether the macro is defined to be legal C.
> 
> 
> 
> 
>