Re: macros: "do-while" versus "({ })" and a compile-time error

Stefan Richter
2007-01-09T17:33:22Z

Robert P. J. Day wrote:
> just to stir the pot a bit regarding the discussion of the two
> different ways to define macros,

You mean function-like macros, right?

> i've just noticed that the "({ })"
> notation is not universally acceptable. i've seen examples where
> using that notation causes gcc to produce:
>
> error: braced-group within expression allowed only inside a function

And function calls and macros which expand to "do { expr; } while (0)"
won't work anywhere outside of functions either.

> i wasn't aware that there were limits on this notation. can someone
> clarify this? under what circumstances *can't* you use that notation?
> thanks.

The limitations are certainly highly compiler-specific.
--
Stefan Richter
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