char is always UTF-8 codepoint and therefore exactly 1 byte. wchar is always UTF-16 codepoint and therefore exactly 2 bytes. dchar is always UTF-32 codepoint and therefore exactly 4 bytes;
You mean "code unit". There's no such thing as a utf-8/16/32 codepoint. A codepoint is a more abstract concept that is encoded in one of the utf formats.
