我正在编写一个程序,在现有链表的末尾添加一个节点。
问题是它似乎没有分配给变量 nr
的struct node
链表最后一个元素的硬编码值 7
。
这是代码:
#include<stdio.h>
#include<stdlib.h>
struct node {
int nr;
struct node *next;
};
void addNodes(struct node **head, int n);
void displayList(struct node *head);
void addItemLast(struct node *head);
int main() {
struct node* head = NULL;
int n;
printf("Introduceti numarul de noduri: ");
scanf("%d", &n);
addNodes(&head, n);
displayList(head);
addItemLast(head);
displayList(head);
return 0;
}
void addNodes(struct node **head, int n) {
*head = (struct node*)malloc(sizeof(struct node));
struct node *current = *head;
printf("\nIntroduceti %d noduri:\n", n);
for(int i = 0; i < n; i++) {
printf("Element %d = ", i+1);
scanf("%d", &(current -> nr));
current->next = (struct node*)malloc(sizeof(struct node));
current = current->next;
}
current->next = NULL;
}
void displayList(struct node *head) {
struct node *current = head;
int i = 1;
printf("\nElementele introduse sunt:\n");
while(current->next != NULL) {
printf("Elementul %d = %d\n", i, current->nr);
current = current->next;
i++;
}
}
void addItemLast(struct node *head) {
struct node *temp = head, *last;
last = (struct node*)malloc(sizeof(struct node));
if(last == NULL) {
printf("\nMemory cannot be allocated!\n");
} else {
last->nr = 7;
last->next = NULL;
while(1) {
if(temp->next == NULL) {
temp->next = last;
break;
}
temp = temp->next;
}
}
}
最后一个函数,addItemLast()
,未按预期工作。
这是输出:
Introduceti numarul de noduri: 3
Introduceti 3 noduri:
Element 1 = 1
Element 2 = 2
Element 3 = 3
Elementele introduse sunt:
Elementul 1 = 1
Elementul 2 = 2
Elementul 3 = 3
有问题的函数运行后,我得到以下输出:
Elementele introduse sunt:
Elementul 1 = 1
Elementul 2 = 2
Elementul 3 = 3
Elementul 4 = 13383248
元素 4 不包含硬编码值 7
,但有一个垃圾值,我不明白为什么。
最佳答案
您的 addNodes
实现不正确,假设我输入 n = 2
,创建了 3 个节点,但只调用了两次 scanf
函数,因此,您在某些节点中有垃圾值(nr
未设置)。
重新实现它(如果 addItemLast
函数正确实现,它就可以工作):
void addNodes(struct node **head, int n){
printf("\nIntroduceti %d noduri:\n", n);
for(int i = 0; i < n; i++){
struct node* last = addItemLast(*head);
if (*head == NULL)
*head = last;
printf("Element %d = ", i);
scanf("%d", &(last -> nr));
}
}
<小时/>
当您想要调用此函数但 head
为 NULL
时,您需要更改 addItemLast
来处理这种情况(无需测试您的程序的这种情况)为空列表调用 addItemLast
时崩溃):
struct node* addItemLast(struct node *head){
struct node *temp = head, *last;
last = (struct node*)malloc(sizeof(struct node));
if (head == NULL) // <---------
{
last->nr = 7;
last->next = NULL;
return last;
}
if(last == NULL){
printf("\nMemory cannot be allocated!\n");
}else{
last->nr = 7;
last->next = NULL;
while(1){
if(temp->next == NULL){
temp->next = last;
break;
}
temp = temp->next;
}
}
return last;
}
<小时/>
最后显示列表的函数应该是:
void displayList(struct node *head){
struct node *current = head;
int i = 1;
printf("\nElementele introduse sunt:\n");
while(current != NULL){ // <---------
printf("Elementul %d = %d\n", i, current->nr);
current = current->next;
i++;
}
}
关于C 链表在末尾添加项,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/52442765/