Question

/*you cannot change anything from here below*/
main()
{
exit(0);
}
/*you cannot change anything from here up*/

This was asked during an interview.

I was told to print something on console.

anybody?

Answer 1

One implementation defined way would be to use the pragma directives to print during compilation.

#pragma message "Compiling " __FILE__ "..."

Or, you could do this with some macros and a printf (but not without introducing UB in some aspect or the other) at runtime.

#define exit(x) printf("Hello, world!")
int main() {
 exit(0); 
 return 0; /* if pre-C99 */
}