#error?

[N8MNAqkS]

What is this for, all it does is post an error message and stop the program from running. Is there any practical use for this, or is it just a thing because it can be.

[Duthomhas]

It has nothing to do with your program. It stops the compiler from running. Use it to indicate that compilation cannot continue unless something necessary is fixed.

[dutch]

#ifdef _WIN32
#error Nope! No way! Sorry, but no.
#endif