关于链接列表中节点的混淆

I have a question about Linked Lists. I spoke to a friend and am now confused. Suppose that there are two variables of type struct node. One is ptr and the other is the header node.

我有关于链接列表的问题。我跟朋友说过话,现在很困惑。假设有两个类型为struct node的变量。一个是ptr,另一个是标题节点。

struct node
{
  int data;
  struct node *link;
};
struct node *ptr,*header;

What is the difference between

有什么区别

ptr=header

and

ptr->link=header

and

ptr->link=header->link

? Edit:I mean semantically.

?编辑:我的意思是语义。

3 个解决方案

#1

Assuming header is pointing to an allocated node initially, it will look like

假设标头最初指向分配的节点,它看起来像

                       +----------------+-----------+
                       |                |           |
header  +----------->  |   data         |  link+-----------> other node/NULL
                       |                |           |
                       +----------------+-----------+

After ptr=header, both ptr and header points to the same node

在ptr = header之后,ptr和header都指向同一节点

                       +----------------+-----------+
pointer +----------->  |                |           |
header  +----------->  |   data         |  link+-----------> other node/NULL
                       |                |           |
                       +----------------+-----------+

After ptr->link=header,

                       +----------------+-----------+
pointer +----------->  |                |           |
header  +----------->  |   data         |  link+----------+ 
                +--->  |                |           |     |
                |      +----------------+-----------+     |
                +-----------------------------------------+

after ptr->link=header->link, it would depend on where header and ptr are pointing

在ptr-> link = header-> link之后,它将取决于header和ptr指向的位置

if they point to the same node then this statement will have no effect.

如果它们指向同一节点,那么此语句将不起作用。

if they point to some different nodes then link pointer of both nodes pointed by ptr and header will point to the same node (or NULL).

如果它们指向某些不同的节点,那么由ptr和header指向的两个节点的链接指针将指向同一节点(或NULL)。

                       +----------------+-----------+
                       |                |           |
header  +----------->  |   data         |  link+--------------+                                                       |
                       |                |           |         |
                       +----------------+-----------+         +------> |
                                                                       |other node/NULL 
                                                              +------> |
                       +----------------+-----------+         |
                       |                |           |         |
ptr     +----------->  |   data         |  link+--------------+ 
                       |                |           |
                       +----------------+-----------+

#2

Assuming you execute only one of these cases:

假设您只执行以下一种情况:

ptr=header would make a pointer to the header node. This means the data of ptr would be the same as the data in header. ptr->link would also be the same as header->link

ptr = header将生成指向头节点的指针。这意味着ptr的数据与标题中的数据相同。 ptr-> link也与header-> link相同

ptr->link=header moves ptr infront of header in the list

ptr-> link = header移动列表中标题的ptr infront

ptr->link = header->link makes ptr parallel to header, e.g.:

ptr-> link = header-> link使ptr与标题并行,例如:
```
ptr->data != header->data; // TRUE
a = ptr->link;
b = header->link;
a->data == b->data // TRUE
```

where a and b are of type struct node*

其中a和b的类型为struct node *

#3

The best way to understand is to draw it out.

理解的最好方法是把它画出来。

#1