[01 什么是变量](01%E4%BB%80%E4%B9%88%E6%98%AF%E5%8F%98%E9%87%8F.md) [02 变量的使用](02%E5%8F%98%E9%87%8F%E7%9A%84%E4%BD%BF%E7%94%A8.md) [03 变量命名规格和规范](03%E5%8F%98%E9%87%8F%E5%91%BD%E5%90%8D%E8%A7%84%E6%A0%BC%E5%92%8C%E8%A7%84%E8%8C%83.md) [04 交换两个变量](04%E4%BA%A4%E6%8D%A2%E4%B8%A4%E4%B8%AA%E5%8F%98%E9%87%8F.md)