Today I just finish reading and experimenting on C about how to use #define to create a manifest constant, after that something came into my mind, and below is the code.
#include <stdio.h>
#define dummy main
#define yam {
#define apple }
int dummy(void) //constant substitution main with dummy
yam // constant substitution { with yam
printf("It works!!\n");
return 0;
apple //constant substitution } with apple
As expected, it works like charm, I just wonder why something like that didn't cause any error, maybe I could understand why the main() could be substituted because main is an identifier (name given to a function, variable and constant), but why the {} can be substituted with a symbolic name too? The second thing is, what data type C use to store this symbolic constant which is not a character enclosed in single quote "" nor an integer or floating-point number.
The #define statements are evaluated by a preprocessor before the program is actually compiled, so the compiler never sees yam. The preprocessor performs a direct text substitution.
That is to say, when the compiler sees your code, it looks like this:
int main(void) //constant substitution main with dummy
{ // constant substitution { with yam
printf("It works!!\n");
return 0;
} //constant substitution } with apple