question

[Echo Yang]

#define cat(x,y) x##y concatenates x to y. But cat(cat(1,2),3) does not expand but gives preprocessor warning. Why?

On Tue, Nov 1, 2011 at 3:42 PM, Echo Yang <sleep...@gmail.com> wrote:

What is the output of printf("\nab\bcd\ref");

the output is: ef

lazy to check out why, please knowledge me.

thanks.