C语言反转链表程序无法输出反转整数列表，请求技术帮助

你的问题出在打印原始链表时修改了head指针，导致后续反转操作传入的是NULL，自然无法得到有效的反转链表。

具体问题点 #

在打印原始链表的循环中，你直接操作了head指针：

printf("Data entered in the list:\n");
while (head != NULL) {
        printf("%d ", head->value);
        head = head->next; // 这里把head移到了链表末尾的NULL
}

循环结束后，head的值已经是NULL，此时调用reverse_list(head)相当于传入NULL，返回的自然也是NULL，所以反转后的链表为空。

修复方案 #

打印链表时使用临时指针遍历，保留原head指针的指向：

修改main函数中打印原始链表的部分：

printf("Data entered in the list:\n");
struct node* temp = head; // 用临时指针遍历
while (temp != NULL) {
        printf("%d ", temp->value);
        temp = temp->next; // 移动临时指针，不修改原head
}
printf("\n");

完整修正后的代码 #

#include <stdio.h>
#include <stdlib.h>

struct node {
        int value;
        struct node* next;
};

struct node* create_node(int value) {
        struct node* new_node = (struct node*)malloc(sizeof(struct node));
        if (new_node == NULL) {
                printf("Error allocating memory.\n");
                exit(1);
        }
        new_node->value = value;
        new_node->next = NULL;
        return new_node;
}

void insert_node_end (struct node** head, int value) {
        struct node* new_node = create_node(value);
        if (*head == NULL) {
                *head = new_node;
        } else {
                struct node* current = *head;
                while (current->next != NULL) {
                        current = current->next;
                }
                current->next = new_node;
        }
}

struct node* reverse_list(struct node* head) {
        struct node* prev = NULL;
        struct node* current = head;
        struct node* next = NULL;

        while (current != NULL) {
                next = current->next;
                current->next = prev;
                prev = current;
                current = next;
        }

        return prev;
}

int main() {
        struct node* head = NULL;
        int value;

        printf("Enter a list of integers. Press ctrl-d to finish.\n");
        while (scanf("%d", &value) != EOF) {
                insert_node_end(&head, value);
        }

        printf("Data entered in the list:\n");
        struct node* temp = head; // 新增临时指针
        while (temp != NULL) {
                printf("%d ", temp->value);
                temp = temp->next; // 移动临时指针
        }
        printf("\n");

        head = reverse_list(head);

        printf("List in reverse order:\n");
        while (head != NULL) {
                printf("%d ", head->value);
                head = head->next;
        }
        printf("\n");

        return 0;
}

验证效果 #

运行修正后的代码，输入7、6、5并按Ctrl+D，输出会符合预期：

Enter a list of integers. Press ctrl-d to finish.
7
6
5
Data entered in the list:
7 6 5 
List in reverse order:
5 6 7 

内容的提问来源于stack exchange，提问作者Sebastian Llaurador