有谁能告诉我这个链表创建中的错误是什么吗?

Question

内部插入函数头部未更新

#include<iostream>
#include<stdlib.h>
using namespace std;
struct node {
int data;
struct node* next;
}*head = NULL;

void insert(struct node* head, int data) {
struct node * newNode ;
newNode->data = data;
newNode->next = NULL;
if (head == NULL) {
head =newNode;

}
else {
struct node* current = head;
while (current->next != NULL) {
current = current->next;
}
//newNode->next = NULL;
current->next = newNode;
}

}

void display(struct node * head) {
struct node* current = head;
while (current) {
cout << current->data<<endl;
}
}

int main()
{
insert(head, 5);
insert(head, 6);
insert(head, 56);
insert(head, 65);
insert(head, 885);
insert(head, 66);
insert(head, 00);
display(head);
}

Answer 1

代码的问题是您的head在您的功能范围之外仍然是NULL。为了更新它，你必须定义一个指向head的指针。除此之外，还需要为newNode动态分配内存。

void insert(struct node** head, int data) {
struct node * newNode = new node() ;
newNode->data = data;
newNode->next = NULL;
if (*head == NULL) {
*head = newNode;
}
else {
struct node* current = *head;
while (current->next != NULL) {
current = current->next;
}
//newNode->next = NULL;
current->next = newNode;
}      
}

Frommain()callinsertfunction as:insert(&head, 5);.

你的代码中的另一个问题是在display函数中，你没有将current更新为current->next。

while (current) {
cout << current->data << endl;
current = current->next;
}