我知道下面的代码很简单，但我一直坚持如何实现它以获得正确的输出。感到非常沮丧。
struct node
{
node* p_next;
int p_data;
node(node* head, int data)
{
p_next = head;
p_data = data;
}
explicit node(int data)
{
node(nullptr, data);
}
};
所以我在C ++中使用这个结构来构造一些链表。
然后我有插入函数将一些节点插入到该链表
node* insert_node(node* head, int data)
{
return new node(head, data);
}
在这里，我开始变得愚蠢。我如何实际制作一些带有实际值的链表？我很困惑如何首先构建一个列表并添加一些值。
我一直在尝试以下操作但却出错。
struct node node_01(1);
node* node_ptr_01 = new node(1);
我想做什么。
我不知道如何初始化head的指针并在其上添加值。
请帮帮我。我将不胜感激。
答案 0 :(得分：1)
在explicit构造函数中，对node(nullptr, data);的调用位于本地空间，结果在结束}后超出范围。
为什么不能只保存这个构造函数中的值（而不是调用另一个？）：
explicit node(int data)
{
p_next = nullptr;
p_data = data;
}
顺便说一下，您的insert_node功能效果很好：
int main() {
// this testing code produces the correct result
// (assuming you fixed your explicit constructor):
node node_01(9);
node* node_ptr_01 = new node(1);
cout << node_01.p_data << endl;
cout << node_ptr_01->p_data << endl;
node* n = insert_node(node_ptr_01, 5);
cout << n->p_data;
cin.get();
}
答案 1 :(得分：1)
请仔细阅读我在c ++中实现链表的方法。我相信它很容易理解
这是 Node.h
#ifndef _NODE_
#define _NODE_
class Node{
private:
char data;
Node* next;
void allocate();
public:
Node();
char getData(void);
Node*getNext();
void setData(char data);
void setNext(Node * next);
~Node();
};
#endif
这是 Node.cpp
#include<iostream>
#include"Node.h"
Node::Node(): data('0'), next(NULL){
std::cout<<"Node created"<<std::endl;
}
void Node::setData(char data){
this->data=data;
}
void Node::setNext(Node *next){
this->next=next;
}
char Node::getData(void){
return data;
}
Node* Node:: getNext(void){
return next;
}
Node::~Node(){
std::cout<<"Node deleted"<<std::endl;
}
这是 linkedList.h
#include"Node.h"
#ifndef Linked_
#define Linked_
class LinkedList{
private:
Node* head;
Node* createNode();
Node* getToLastNode();
int getLength();
char getUserData();
public:
LinkedList();
void addNodeAtTheBeginning();
void addNodeAtAGivenLocation(int);
void addNodeAtTheEnd();
void deleteFirstNode();
void deleteNodeAtAGivenLocation(int);
void deleteLastNode();
void display();
void deleteLinkedList();
~LinkedList();
};
#endif
这是 LinkedList.cpp
#include"Node.h"
#include"LinkedList.h"
#include<iostream>
Node* LinkedList::createNode(){
Node *tempNode;
tempNode = new Node();
tempNode->setNext(NULL);
tempNode->setData(getUserData());
return tempNode;
}
int LinkedList::getLength(){
Node *tempNode=head;
int count=1;
if(NULL==head){
return 0;
}else{
while(NULL!=tempNode->getNext()){
tempNode=tempNode->getNext();
count++;
}
return count;
}
}
LinkedList::LinkedList(){
head=NULL;
// if(NULL==head){
// head=createNode();
// }
}
void LinkedList::addNodeAtTheBeginning(){
Node *tempNode;
tempNode=createNode();
if(NULL!=head){
tempNode->setNext(head);
head=tempNode;
}else{
head=tempNode;
}
}
void LinkedList::addNodeAtAGivenLocation(int position){
Node *tempNode;
Node *tempNode2;
if(getLength()<position){
std::cout<<"No node can be inserted at this poition "<<std::endl;
}else{
tempNode=createNode();
tempNode2=head;
for(int i=1;i<position;i++){
tempNode2=tempNode2->getNext();
}
tempNode->setNext(tempNode2->getNext());
tempNode2->setNext(tempNode);
}
}
void LinkedList::addNodeAtTheEnd(){
if(NULL==head){
head=createNode();
}else{
Node *tempNode=head;
while(NULL!=tempNode->getNext()){
tempNode=tempNode->getNext();
}
tempNode->setNext(createNode());
}
}
void LinkedList::deleteFirstNode(){
Node *tempNode;
if(NULL==head){
std::cout<<"No node available for deletion"<<std::endl;
}else{
tempNode=head;
head=head->getNext();
delete tempNode;
}
}
void LinkedList::deleteNodeAtAGivenLocation(int position){
Node *tempNode;
if(getLength()<=position){
std::cout<<"No node can be deleted as no node exist at this poition "<<std::endl;
}else{
for(int i=1;i<position;i++){
tempNode=head;
tempNode=tempNode->getNext();
}
tempNode->setNext(tempNode->getNext()->getNext());
delete tempNode->getNext();
}
}
void LinkedList::deleteLastNode(){
Node *tempNode;
Node *tempNode2;
if(NULL==head){
std::cout<<"No node available for deletion"<<std::endl;
}else{
tempNode=head;
while(NULL!=tempNode->getNext()){
tempNode=tempNode->getNext();
tempNode2=tempNode;
}
tempNode=tempNode->getNext();
tempNode2->setNext(NULL);
delete tempNode;
}
}
LinkedList::~LinkedList(){
Node *tempNode=NULL;
if(NULL==head){
std::cout<<"No nodes in the Linked List available for Deletion"<<std::endl;
}else{
tempNode =head;
while(NULL!=head->getNext()){
tempNode=head;
head=head->getNext();
delete tempNode;
}
delete head;
}
std::cout<<"Linked List Deleted"<<std::endl;
head=NULL;
}
void LinkedList::display(void){
Node *tempNode;
tempNode=head;
if(NULL==head){
std::cout<<"head-->X";
}else{
std::cout<<"head-->";
while(NULL!=tempNode->getNext()){
std::cout<<"["<<tempNode->getData()<<"]-->";
tempNode=tempNode->getNext();
}
std::cout<<"["<<tempNode->getData()<<"]-->X"<<std::endl;
}
}
void LinkedList::deleteLinkedList(){
delete this;
head=NULL;
}
char LinkedList::getUserData(){
char data;
std::cout<<"Enter Data"<<std::endl;
std::cin>>data;
return data;
}
最后是 main.cpp
#include <cstdlib>
#include <iostream>
#include"LinkedList.h"
#include"Node.h"
#include<stdlib.h>
void printMenu();
int getUserSelection();
void performOperation(int);
LinkedList lk;
int main(){
int option=0;
while(9!=option){
printMenu();
option=getUserSelection();
performOperation(option);
}
}
void printMenu(void){
std::cout<< ""<<std::endl;
std::cout<< "1) Add Node At The Beginning"<<std::endl;
std::cout<< "2) Add Node At A Given Location"<<std::endl;
std::cout<< "3) Add Node At The End"<<std::endl;
std::cout<< "4) Delete First Node"<<std::endl;
std::cout<< "5) Delete Node At A Given Location"<<std::endl;
std::cout<< "6) Delete Last Node"<<std::endl;
std::cout<< "7) Display "<<std::endl;
std::cout<< "8) Delete LinkedList"<<std::endl;
std::cout<< "9) Exit"<<std::endl;
}
int getUserSelection(){
int option=0;
std::cout<<"Select an option: "<<std::endl;
std::cin>>option;
return option;
}
void performOperation(int option){
switch (option){
case 1:
lk.addNodeAtTheBeginning();
break;
case 2:{
int location=0;
std::cout<<"Enter a location:"<<std::endl;
std::cin>>location;
lk.addNodeAtAGivenLocation(location);
}
break;
case 3:
lk.addNodeAtTheEnd();
break;
case 4:
lk. deleteFirstNode();
break;
case 5:{
int location=0;
std::cout<<"Enter a location:"<<std::endl;
std::cin>>location;
lk.deleteNodeAtAGivenLocation(location);
}
break;
case 6:
lk.deleteLastNode();
break;
case 7:
lk.display();
break;
case 8:
lk.deleteLinkedList();
break;
case 9:
exit(0);
}
}