#define hello(x) sin(x)
hello(x)
hello(2+2)
#define abs(x) (if((x)>0)(x);else -(x);)
abs(3+hello(5))
PI
#define PI 3.14159269
PI
#define fun(x,y,z) sin(x)*cos(y)*tan(z)
fun(1,2,3)

#ifndef TEST
#define mesg test not defined
#else
#define mesg test defined
#endif
mesg