[常量的定义和使用](%E5%B8%B8%E9%87%8F%E7%9A%84%E5%AE%9A%E4%B9%89%E5%92%8C%E4%BD%BF%E7%94%A8.md) [变量](%E5%8F%98%E9%87%8F.md) [枚举](%E6%9E%9A%E4%B8%BE.md)