用结构体理解 typedef [英] Understanding typedef with struct

问题描述

我很难理解这个代码示例:

I am getting a hard time understanding this sample of code:

typedef struct node
{
        int data;
        struct node * next;
} node;

typedef node * nodepointer;

所以，我们正在使用 typedef 构建结构节点......我假设我们这样做是为了在不需要struct"关键字的情况下初始化结构.

So, we are building the struct node using typedef... I assume we are doing this in order to initialize the struct without the "struct" keyword being necessary.

我想问一下为什么在结构定义中我们使用名称节点"两次(在开始和结束处).

I want to ask why in the struct definition we used the name "node" twice (at start and end).

其次是 typedef node * nodepointer; 指向什么.在这种情况下是否有必要使用 typedef?这个表达式 node * nodepointer; 不等于吗?

Secondly what typedef node * nodepointer; points to. Is it necessary to use typedef in this case? Is this expression node * nodepointer; not equal?

推荐答案

问题是您同时在做两件事:声明结构类型和将该结构类型定义为名称.

The question is that you are doing two things at once: declaring struct type and typedefing that struct to a name.

typedef 的语法是

typedef <some type> name;

其中某些类型可能是简单类型，例如 int、long 等，也可能是复杂的类型，例如 struct foo，而这不管 struct foo 之前是否已经声明过，或者在那个时候声明过.

where some type may be a simple type, like int, long, etc. or a complex one like struct foo, and this regardless of wether struct foo has been declared before or it's being declared at that very point.

所以

typedef struct foo { int bar; } foo;

对应

typedef <some type> name;

其中 是 struct foo { int bar;} 和 name 是 foo

where <some type> is struct foo { int bar; } and name is foo

关于第二个问题，

在这种情况下， 是 node * 而 name 是 nodepointer，所以>

In this case <some type> is node * and name is nodepointer, so

typedef node * nodepointer;

正在将 nodepointer 定义为指向 node 的指针(您之前已将其 typedefd 为 struct node { ... })

is typedefing a nodepointer as a pointer to a node (which you have typedefd just before to be a struct node { ... })

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