int와 signed int는 같은데
char과 signed char은 다르다.???
▼ char과 signed char, unsgiend char이 서로 다르다고?
https://jacking.tistory.com/149
▼ char!=(signed char), char!=(unsigned char) [duplicate]
https://stackoverflow.com/questions/436513/char-signed-char-char-unsigned-char