The question is what mean?

CodePudding user response:

 
# define 3 P 
# define S (a) P * a * a 
The main {
Int ar; 
Ar=S (3 + 5) 
Printf (" \ n % d ", ar); 
} 

Ar=S (3 + 5) unfolds into ar=3 * 3 * 3 + 5 + 5, not what you think of ar (3 + 5=3 * * (3 + 5), so the calculated 29, not 192,
To get 192, # define S (a) P * a * b to change to # define S P * * (a) (a) (a), pay attention to the enclosed, a