我无法理解这个简单代码的意义
我正在做这项作业，有一些东西（来自启动材料）我无法理解。
typedef enum
{
NORTH,
EAST,
SOUTH,
WEST,
NUM_POINTS
} Point;
typedef Point Course[NUM_POINTS] ;
我不明白最后一行背后的想法，如何在代码中使用它？
I am doing this assignment, and there are some stuff (from start-up materials) that I cannot comprehend.
typedef enum
{
NORTH,
EAST,
SOUTH,
WEST,
NUM_POINTS
} Point;
typedef Point Course[NUM_POINTS] ;
I don't get the idea behind the last line , and how can I use it in the code?
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使
b成为类型a的别名，例如两个
bar是等效的。在您的情况下，使
Course成为类型Point[NUM_POINTS]的别名（其中NUM_POINTS == 4），因此是等效的。
Makes
ban alias for typea, e.g.both
bars are equivalent. In your case,Makes
Coursean alias for typePoint[NUM_POINTS](whereNUM_POINTS == 4), soare equivalent.
由于
NUM_POINTS是枚举中的最后一个条目，因此它具有最高值，并且是其他值的计数。如果 NUM_POINTS 不打算用作 Point 的实际值，那么最后一行的目的似乎是为大小等于点数量的点数组创建类型名称。 “真实”点。这里有一个很好的功能：如果您向枚举添加更多值（例如
NORTH_EAST、SOUTH_WEST等）之前NUM_POINTS 时，typedef 行将自动保持正确，因为NUM_POINTS的值会由于在其之前插入的新值而增大。Since
NUM_POINTSis the last entry in the enum, it has the highest value, and is the count of the other values. IfNUM_POINTSis not meant to be used as an actual value for a Point, it looks like the purpose of the last line is to create a type name for an array of points of size equal to the number of "real" points.Here's one nice feature: if you add more values to the enum (like
NORTH_EAST,SOUTH_WEST, etc.) beforeNUM_POINTS, the typedef line will automatically still be correct, because the value ofNUM_POINTSwill have grown because of the new values inserted before it.枚举从 0 开始，每个值加 1。
所以你有：
NORTH = 0，EAST = 1，SOUTH = 1，WEST = 3，NUM_POINTS = 4NUM_POINTS设置为枚举中的项目数。最后一行为包含 4 个元素的点数组创建了 Course 的别名。语法有点混乱，因为数组下标位于
Course之后，而不是Point旁边。然而，它的工作方式与例如相同：
[10]部分位于变量名称而不是类型旁边。an enum starts at 0 and increases by 1 for each value.
So you have:
NORTH = 0,EAST = 1,SOUTH = 1,WEST = 3,NUM_POINTS = 4NUM_POINTSis set to the number of items in the enum.The last line creates an alias of Course for a point array with 4 elements in it. The syntax is a little confusing because the array subscript is after
Courseand not next toPoint.However it does work the same way as for example:
The
[10]part is next to the variable name not the type.这意味着 Course 可用于表示 Points 数组，其中 NUM_POINTS 是数组中的项目数。
It means that Course can be used to represent an array of Points, with NUM_POINTS being the number of items in the array.