What is the difference between quot;structquot; and lack of quot;structquot; word before member of a struct(“struct和“struct有什么区别?并且缺乏“结构结构体成员之前的词)
问题描述
我必须创建简单的 List 实现.他们想要将 struct
放在 Node
类的成员 next
之前.为什么有struct
这个词,没有它有什么区别?
I have to create simple List implementation. They guy who wants that put struct
before member next
of class Node
. Why is there a struct
word, what would be the difference without it?
struct Node{
int value;
struct Node *next;//what is this struct for?
};
struct List{
struct Node *first, *last;
};
推荐答案
在您的示例中,无需在 next
声明之前使用 struct
关键字.在需要时,它通常被认为是 C 的回退.在 C++ 中,这就足够了:
In your example, there is no need to use the struct
keyword before the next
declaration. It is usually considered a throw-back from C, where it is required. In C++, this would suffice:
struct Node{
int value;
Node *next;
};
但是,如果您有一个名为 Node
的成员,那么您将必须使用 struct
或 class
:
However, if you had a member called Node
, then you would have to use struct
or class
:
struct Node{
int Node;
struct Node *next; // struct or class required here
};
对于尚未定义的类型的声明(前向声明),您还需要 class
的 struct
.例如
You would also require struct
of class
for a declaration of a type that is not yet defined (a forward declaration). For example
struct Foo {
class Bar* bar_; // Bar defined later
};
我使用 class
来显示它在这种情况下没有区别.
where I used class
to show it makes no difference in this scenario.
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