[2.1 变量的内部实现](2.1%E5%8F%98%E9%87%8F%E7%9A%84%E5%86%85%E9%83%A8%E5%AE%9E%E7%8E%B0.md) [2.2 数组](2.2%E6%95%B0%E7%BB%84.md) [2.3 静态变量](2.3%E9%9D%99%E6%80%81%E5%8F%98%E9%87%8F.md) [2.4 全局变量](2.4%E5%85%A8%E5%B1%80%E5%8F%98%E9%87%8F.md) [2.5 常量](2.5%E5%B8%B8%E9%87%8F.md)