Adding -い at the end of questions


どうしたんだ vs どうしたんだい

そうか vs そうかい

This kind of thing. Is it a formality difference? Is it dialectical/Regional?
Age related?




The i at the end is a shortened form of yo Sou kai = sou ka yo. Doushita ndai
= doushita nda yo.

Its slang.

