[变量的类型](%E5%8F%98%E9%87%8F%E7%9A%84%E7%B1%BB%E5%9E%8B.md) [变量赋值](%E5%8F%98%E9%87%8F%E8%B5%8B%E5%80%BC.md) [变量求值](%E5%8F%98%E9%87%8F%E6%B1%82%E5%80%BC.md) [预定义变量](%E9%A2%84%E5%AE%9A%E4%B9%89%E5%8F%98%E9%87%8F.md)