paste.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

/* Test for proper comment elimination semantics from cpplib's -traditional.
   This should compile and link with compiled with `gcc -traditional-cpp'.
   Test case by Jason R. Thorpe <[e-mail]>.  */

/* { dg-do compile } */

#define A(name) X/**/name

#define B(name) \
void A(Y/**/name)() { A(name)(); }

void Xhello() { printf("hello world\n"); }

B(hello)

int main() { XYhello(); return (0); }