How this program behaves at execution.....

Question

#define TRUE
#define FALSE

main() {
#ifdef TRUE && FALSE
printf ("true") ;
#else
printf("false");
#endif
}

Answer 1

Here true and false Are predefined
And in 1st case true && false will result in 0 which means
Else will be executed, it will print false

Answer 2

It seems like this code prints true despite being syntactically incorrect. #ifdef just checks whether TRUE is somehow defined, which it is, and the rest with the && FALSE doesn't matter. Or in other words the compiler ignores the incorrect instructions "&&" and "FALSE" but it could throw an error as well. And you also need to write int main, not just main :)