如何制作C中的链表

Question

使用两个链表或类似的东西，我想添加"ABCD"；，那么我想得到"；ABDC"；。

我不确定我的代码是否正确，我是C.的一个角落

代码应该有指针和malloc。我做的是这样的：

struct Node
{
char data;
struct Node* next;
};
struct Node* newNode(char data)
{
struct Node* node = (struct Node*)malloc(sizeof(struct Node));
node->data = data;
node->next = NULL;
return node;
}
struct Node* constructList()
{
struct Node* first = newNode(1);
struct Node* second = newNode(2);
struct Node* third = newNode(3);
struct Node* forth = newNode(4);
struct Node* head = first;
first->next = second;
second->next = third;
third->next=forth;
return head;
}
void printList(struct Node* head)
{
struct Node* ptr = head;
while (ptr)
{
printf("%d -> ", ptr->data);
ptr = ptr->next;
}
printf("NULL");
}

Answer 1

您的代码很好，尽管它缺乏错误处理(为什么要使用char来存储整数？(。

确保在使用完节点后free()，例如：

void freeList(struct Node* head)
{
struct Node* ptr = head;
struct Node* next;
while (ptr)
{
next = ptr->next;
free(ptr);
ptr = next;
}
}

我建议将constructList()更改为使用循环，例如：

struct Node* constructList()
{
struct Node *head = NULL;
struct Node **ptr = &head;
for (int value = 1; value <= 4; ++value)
{
*ptr = newNode(value);
if (*ptr == NULL)
{
freeList(head);
return NULL;
}
ptr = &((*ptr)->next);
}
return head;
}

然后，您可以将constructList()泛化为采用整数数组或字符串作为输入，并在该输入中循环，为每个值添加一个新节点。例如，试试这个：

struct Node
{
char data;
struct Node* next;
};
struct Node* newNode(char data)
{
struct Node* node = (struct Node*) malloc(sizeof(struct Node));
if (node)
{
node->data = data;
node->next = NULL;
}
return node;
}
void freeList(struct Node* head)
{
struct Node* ptr = head;
struct Node* next;
while (ptr)
{
next = ptr->next;
free(ptr);
ptr = next;
}
}
struct Node* constructList(const char *str)
{
struct Node *head = NULL;
struct Node **ptr = &head;
char ch;
if (str)
{
while ((ch = *str++) != '')
{
*ptr = newNode(ch);
if (*ptr == NULL)
{
freeList(head);
return NULL;
}
ptr = &((*ptr)->next);
}
}
return head;
}
void printList(struct Node* head)
{
struct Node* ptr = head;
while (ptr)
{
printf("%c -> ", ptr->data);
ptr = ptr->next;
}
printf("NULL");
}

struct Node *list = constructList("ABCD");
printList(list);
freeList(list);