“struct"和“struct"有什么区别?并且缺乏“结构"结构体成员之前的词 [英] What is the difference between "struct" and lack of "struct" word before member of a struct

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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