They are obviously not considered good practice. The proof: they don't exist in Wirth's languages (Pascal, Modula-2, Oberon). Wirth, Ichbiah and Meyer define

They are obviously not considered good practice. The proof: they don't exist in Wirth's languages (Pascal, Modula-2, Oberon). Wirth, Ichbiah and Meyer define good practice, not Kernighan, Ritchie, or Thompson, and much less Stroustrup.