c - 奇怪的数字出现在输出-C

Question

我做了一个像这样的简单列表:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
 struct node{
    int am;
    struct node *next;
};
typedef struct node node;
int main(){
int n;
    node *head=(node *)malloc(sizeof(node));
    node *cur=head;
    printf("Give me a number:\n");
    scanf(" %d",head->am);
    cur=head;
    while(1){
        printf("Give me a number\n");
        scanf(" %d",&n);
        if(n==0)
            break;
        cur->am=n;
        cur->next=(node *)malloc(sizeof(node));
        cur=cur->next;
        cur->next=null;
    }
    travel(head);
    printf("Total nodes available :%d\n",count(head));
    system("pause");
    return 0;
}

现在旅行应该遍历列表中的每个节点并显示每个节点中保存的整数。

void travel(node *h){
    if(h==NULL)
        return;
    printf("Received data from node: \t %d\n",h->am);
    travel(h->next);
} 

现在的问题是，当调用 travel 时，它不会打印第一个节点的整数。它还会打印另一个“从节点接收的数据:”后跟一个奇怪的数字。例如如果我给 1,2,3,4 作为输入，这些就是结果

Received data from node:         2
Received data from node:         3
Received data from node:         4
Received data from node:         4026432

有什么想法吗？

Answer 1

Now the problem is that when travel is called it wont print the integer from the first node

从main()函数的这部分可以准确知道

printf("Give me a number:\n");
scanf(" %d",head->am); //this is wrong use of scanf("%d",&head->am);
cur=head;
while(1){
    printf("Give me a number\n");
    scanf(" %d",&n);
    if(n==0)
        break;
    cur->am=n;

正如我所提到的，您扫描错误，但这并不重要，因为稍后在 while 循环中的代码中，您将以这种方式替换它...

• 你扫描号码并将其存储在head->am
• 然后将 head 分配给 cur 所以 head->am 和 cur->am 都是现在相同...所以在 while 循环中，当您第一次将 n 分配给 cur->am 时，它会分配给 head->am。所以这就解释了为什么您永远无法打印第一个节点。

---

解决方案:

• 克服它...在 while 循环中，在分配 cur->am=n 之前尝试做:

  cur->next=(node *)malloc(sizeof(node));
  cur=cur->next;
  //then... assign
  curr->am=n;
  

这样你就不会丢失第一个节点。

---

建议:

正如有人已经说过的那样，使用循环遍历/遍历列表要容易得多(没关系......如果你想递归地这样做)

这是你如何使用循环来完成它:

 void travel(node *h)
 {
    if(h==NULL)
        return; //list is empty,consider printing "list empty" :)
    while(h!=NULL)
    {
        printf("Received data from node: \t %d\n",h->am);
        h=h->next;
    }
} 

---

在不按照建议更改 travel() 函数的情况下将所有代码放在一起:

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

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

typedef struct node node;

void travel(node *h);

int main() //I have a habit of returning values from main() :)
{
    int n;
    node *head=(node *)malloc(sizeof(node));
    node *cur=head;
    printf("Give me a number:\n");
    scanf(" %d",&head->am);
    cur=head;
    while(1)
    {
        printf("Give me a number\n");
        scanf(" %d",&n);
        if(n==0)
            break;
        cur->next=(node *)malloc(sizeof(node));
        cur=cur->next;
        cur->am=n;                     //NOTE:here's the change!
        cur->next=NULL;
    }
    travel(head);
    return 0; //just to signify successful compilation
}

void travel(node *h)
{
    if(h==NULL)
        return;
    printf("Received data from node: \t %d\n",h->am);
    travel(h->next);
}

示例输入: 5 6 3 1 0

示例输出:

Give me a number:
5
Give me a number
6
Give me a number
3
Give me a number
1
Give me a number
0
Received data from node:     5
Received data from node:     6
Received data from node:     3
Received data from node:     1