如何在C中执行在链接列表中插入、删除和显示元素

Question

我正在用C编写一个我还不太熟悉的程序。它可以选择如何处理链表。但它也有错误。到目前为止，这就是我所拥有的。

#include<stdio.h>
#include<stdlib.h>
struct node
{
    int data;
    struct node *next;
}*head;

void append(int num)
{
    struct node *temp,*right;
    temp= (struct node *)malloc(sizeof(struct node));
    temp->data=num;
    right=(struct node *)head;
    while(right->next != NULL)
    right=right->next;
    right->next =temp;
    right=temp;
    right->next=NULL;
}

void add( int num )
{
    struct node *temp;
    temp=(struct node *)malloc(sizeof(struct node));
    temp->data=num;
    if (head== NULL)
    {
    head=temp;
    head->next=NULL;
    }
    else
    {
    temp->next=head;
    head=temp;
    }
}
void addafter(int num, int loc)
{
    int i;
    struct node *temp,*left,*right;
    right=head;
    for(i=1;i<loc;i++)
    {
    left=right;
    right=right->next;
    }
    temp=(struct node *)malloc(sizeof(struct node));
    temp->data=num;
    left->next=temp;
    left=temp;
    left->next=right;
    return;
}
int count()
{
    struct node *n;
    int c=0;
    n=head;
    while(n!=NULL)
    {
    n=n->next;
    c++;
    }
    return c;
} 

void insert(int num)
{
    int c=0;
    struct node *temp;
    temp=head;
    if(temp==NULL)
    {
    add(num);
    }
    else
    {
    while(temp!=NULL)
    {
        if(temp->data<num)
        c++;
        temp=temp->next;
    }
    if(c==0)
        add(num);
    else if(c<count())
        addafter(num,++c);
    else
        append(num);
    }
}

int delete(int num)
{
    struct node *temp, *prev;
    temp=head;
    while(temp!=NULL)
    {
    if(temp->data==num)
    {
        if(temp==head)
        {
        head=temp->next;
        free(temp);
        return 1;
        }
        else
        {
        prev->next=temp->next;
        free(temp);
        return 1;
        }
    }
    else
    {
        prev=temp;
        temp= temp->next;
    }
    }
    return 0;
}

void  display(struct node *r)
{
    r=head;
    if(r==NULL)
    {
    return;
    }
    while(r!=NULL)
    {
    printf("%d ",r->data);
    r=r->next;
    }
    printf("n");
}

int  main()
{
    int i,num;
    struct node *n;
    head=NULL;
    while(1)
    {
    printf("nList Operationsn");
    printf("===============n");
    printf("1.Insertn");
    printf("2.Displayn");
    printf("3.Sizen");
    printf("4.Deleten");
    printf("5.Exitn");
    printf("Enter your choice : ");
    if(scanf("%d",&i)<=0){
        printf("Enter only an Integern");
        exit(0);
    } else {
        switch(i)
        {
        case 1:      printf("Enter the number to insert : ");
                 scanf("%d",&num);
                 insert(num);
                 break;
        case 2:     if(head==NULL)
                {
                printf("List is Emptyn");
                }
                else
                {
                printf("Element(s) in the list are : ");
                }
                display(n);
                break;
        case 3:     printf("Size of the list is %dn",count());
                break;
        case 4:     if(head==NULL)
                printf("List is Emptyn");
                else{
                printf("Enter the number to delete : ");
                scanf("%d",&num);
                if(delete(num))
                    printf("%d deleted successfullyn",num);
                else
                    printf("%d not found in the listn",num);
                }
                break;
        case 5:     return 0;
        default:    printf("Invalid optionn");
        }
    }
    }
    return 0;
}

Answer 1

我制作了另一个工作程序。看看这个。你可能有一些补充，也许？

#include <iostream>
#include <conio.h>
using namespace std;
class Node {
      int data;
      Node* next;
      public:
             Node() {};
             void SetData(int aData) { data = aData; };
             void SetNext(Node* aNext) { next = aNext; };
             int Data() { return data; };
             Node* Next() { return next; };
};
class List {
      Node *head;
      public:
             List() { head = NULL; };
             void Display();
             void Append(int data);
             void Remove(int data);
};
void List::Display() {
     Node *tmp = head;
     if ( tmp == NULL ) {
          cout << "EMPTY" << endl;
          return;
     }
     if ( tmp->Next() == NULL ) {
          cout << tmp->Data();
          cout << " --> ";
          cout << "NULL" << endl;
          }
     else {
          do {
              cout << tmp->Data();
              cout << " --> ";
              tmp = tmp->Next();
          } while ( tmp != NULL );
     cout << "NULL" << endl;
     }
}
void List::Append(int data) {
     Node* newNode = new Node();
     newNode->SetData(data);
     newNode->SetNext(NULL);
     Node *tmp = head;
     if ( tmp != NULL ) {
          while ( tmp->Next() != NULL ) {
                tmp = tmp->Next();
          }
     tmp->SetNext(newNode);
     }
     else {
          head = newNode;
     }
}
void List::Remove(int data) {
     Node *tmp = head;
     if ( tmp == NULL )
          return;
     if ( tmp->Next() == NULL ) {
          delete tmp;
          head = NULL;
     }
     else {
          Node *prev;
          do {
              if ( tmp->Data() == data ) break;
              prev = tmp;
              tmp = tmp->Next();
          } while ( tmp != NULL );
     prev->SetNext(tmp->Next());
     delete tmp;
     }
}
int main() {
    List list;
    int n[100], i, size;
    char choice;
    for(i=1; i<=100; i++){
             cout<<"Insert[I]nDisplay[D]nRemove[R]n";
             cin>>choice;
             if (choice=='I'||choice=='i'){
                                       cout<<"Enter the number of nodes: ";
                                       cin>>size;
                                       cout<<"Enter a number to be inserted:n";
                                       for(i=1; i<=size; i++){
                                                         cin>>n[i];
                                                         list.Append(n[i]);
                                       }
             }
             if (choice=='D'||choice=='d'){
                                       cout<<"Elements in the list are: ";
                                       list.Display();
             }
             if (choice=='R'||choice=='r'){  
                                       cout<<"Enter a number to be removed: ";
                                       cin>>n[i];
                                       list.Remove(n[i]);
             }
    }
    getch();
}