https://ko.wikipedia.org/wiki/%EB%B6%80%EB%8F%99%EC%86%8C%EC%88%98%EC%A0%90#:~:text=%EC%A7%80%EC%88%98%EC%9D%98%205%EB%A5%BC%20%EC%9D%B4%EC%A7%84
C언어 자료형https://edu.goorm.io/learn/lecture/201/%ED%95%9C-%EB%88%88%EC%97%90-%EB%81%9D%EB%82%B4%EB%8A%94-c%EC%96%B8%EC%96%B4-%EA%B8%B0%EC%B4%88/les