I'm having a problem that can not draw ustr.

such as this question.
link : https://www.allegro.cc/forums/thread/612879

I changed the encoding of a source code file(*.c) to UTF-8 without signature in MSVC,

but when I print out "가나다라마바사" with al_draw_ustr, It print out "가?".

and I print out "나" with al_draw_ustr, MSVC notifies two errors there C2001, C2143

How can I solve this problem?

Is it really necessary to omit the BOM? If you include the BOM does the problem go away?

No, it doesn't work.

When i compile with UTF8(include BOM), it prints null(look likes blank)