Usually, coordinate values are stored in numeric columns (float, decimal, or even integer), and the specific type will not affect the code presented here.
通常，坐标值存储在数字列中(浮点、小数，甚至是整数)，具体的类型并不影响这里给出的代码。
2
The second production describes in regex-like fashion more specifically what an integer literal looks like: a contiguous sequence of one or more numeric digits.
第二个结果以类regex的方式更特定地描述了一个整数值看上去象什么：一个或多个数字的连续序列。
3
Adding methods to Integer allows you to create much more expressive code because you can use real Numbers to represent numeric values.