−1 This doesn't answer the question from the title, “When is #include library demanded in C++?”. I assume that that might be Okay While using the OP. But it's difficulty when this concern is applied as referent for the close-as-duplicate of some other query. What this would mean is https://a-listdirectory.com/listings13475642/chris-brown-under-the-influence-cover-song-no-further-a-mystery