c - 根据用户输入打印链接列表

Question

我是初学者，我正在通过用户输入创建和打印链接列表。创建部分进展顺利，但每次我尝试打印最终列表时，我都会收到恼人的“列表为空”消息。 *stnode 指针可能有问题。有人可以帮我吗？感谢您的每一个回答!

代码

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

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

//function creating the linked list
void createnodelist(int n)
  {
  int num, i;
  struct node *stnode = (struct node*)malloc(sizeof(struct node)), *fnnode, *temp;

  if (stnode==NULL) {
    printf("Memory cannot be located");
    return;
    }

  //creating head of the list
  else {
    printf("Number 1 = ");
    scanf("%d", &num);
    stnode->data = num;
    stnode->next = NULL;
    if (stnode == NULL) {
  printf("Memory can not be located");
      }
    temp = stnode;
    }

  //Creating all others parts of linked list
  for (i=2; i<=n; i++)
    {
    fnnode = (struct node*)malloc(sizeof(struct node));
    if (fnnode==NULL) {
      printf("Memory cannot be located\n");
      break;
      }
    printf("Number %d = ", i);
    scanf("%d", &num);
    fnnode->data = num;
    fnnode->next = NULL;
    temp->next = fnnode;
    temp = temp->next;
    }
  }

//function printing the output
void printnode()
  {
  struct node *n = (struct node*)malloc(sizeof(struct node));

  n = stnode;
  if (stnode == NULL) {
    printf("LIST IS EMPTY"); //HERE IS MY PROBLEM
    }
  while (n!=NULL) {
    printf("%d ", n->data);
    n = n->next;
    }
  }    

int main()
  {
  int n;
  printf("Enter number of elements: ");
  scanf("%d", &n);
  printf("\n");

  createnodelist(n);
  printf("\n");

  printnode();

  printf("\n\n");
  return 0;
  }

Answer 1

在 createnotelist() 中，您使用 stnode 的本地声明隐藏全局 stnode。因此，全局 stnode 保持未定义或为 null，并且不会在 createnodelist() 中进行修改。