解决-错误C2440:“初始化”:不能从“LinkedList *”转换为“LinkedList”

Found the solution - posted in answers.

找到了解决方案——张贴在答案中。

I get this error when I try to compile my LinkedList implementation and I cannot find where the problem lies. It points to this but I cannot find the fault.

当我试图编译我的LinkedList实现时，我得到这个错误，我找不到问题所在。它指向这个，但我找不到错误。

LinkedList my =new LinkedList();

The class and the main function: -

本课程及主要功能:-。

struct Node {
    int data;
    Node* next;
};
class LinkedList {
private:

    public:
        void LinkedList::init_list(struct Node *&head);
        bool LinkedList::is_list_empty(struct Node *head);
        Node* LinkedList::search(struct Node *head,int value);
        int LinkedList::deleteNode(struct Node *head,int value);
        int LinkedList::deleteat(struct Node *&head,int i);
        bool LinkedList::insert(struct Node *&head,int value);
        bool LinkedList::insertat(struct Node *&head,int value, int i);
        int LinkedList::list_length(struct Node *head);
        void LinkedList:: display(struct Node *head);

};

int main(){
    LinkedList my =new LinkedList();
    Node *head;
    Node *&ahead = *&head;
    my.init_list(ahead);
    my.display(head);
    my.insert(ahead,1111);
    //cout<<"1sr time";
    cout<< "length- " <<my.list_length(head)<<endl;
    //cout<< "deleting---  " <<deleteat(ahead,1)<<endl;
    my.insert(ahead,34);
    my.insert(ahead,32);
    my.insert(ahead,44);
    my.display(head);
    cout<<endl;
    my.insertat(ahead,4444,1);
    my.display(head);
    system("Pause");
    return 0;

}

The complete code:-

完整的代码:-

#include <iostream>
#include <exception>


using namespace std;



struct Node {
    int data;
    Node* next;
};
class LinkedList {
private:

    public:
        void LinkedList::init_list(struct Node *&head);
        bool LinkedList::is_list_empty(struct Node *head);
        Node* LinkedList::search(struct Node *head,int value);
        int LinkedList::deleteNode(struct Node *head,int value);
        int LinkedList::deleteat(struct Node *&head,int i);
        bool LinkedList::insert(struct Node *&head,int value);
        bool LinkedList::insertat(struct Node *&head,int value, int i);
        int LinkedList::list_length(struct Node *head);
        void LinkedList:: display(struct Node *head);

};



void LinkedList:: init_list(struct Node*&head){
    head=NULL;
}
bool LinkedList:: is_list_empty(struct Node*head){//returns true(1) if the list is empty
    if (head==NULL){
        return true;
    }
    return false;
}

Node* LinkedList:: search(struct Node*head, int value){
    Node* pointer;
    pointer=head;
    while (pointer->next != NULL){

        if (pointer->data==value){
        cout<<"value found" <<endl;
        return pointer;
    }
    pointer=pointer->next;
    }
    cout<<"value not found!!"<<endl;
    return NULL;
}

int LinkedList:: deleteNode(struct Node *head, int value){
    Node* pointer;
    Node* pointer2;
    pointer=head;
    while (pointer != NULL){
        pointer2 = pointer->next;
        if(pointer2 !=NULL && pointer2->data==value){
            pointer->next=pointer2->next;
            return pointer2->data;
        }
        else if(pointer2==NULL){
            cout<<"value not here - cannot delete";
            return NULL;
        }
        pointer=pointer->next;
    }
}


int LinkedList:: list_length(struct Node*head){
    int count=0;
    Node* p = head; 
    while (p != NULL) 
{ 
  ++count; 
  p = p->next; 
}
    return count;
}

int LinkedList:: deleteat(struct Node *&head, int loc){
    int i=2;
    Node*pointer =head;
    Node* pointer2;
    if(list_length(head)<loc || loc<1){
        cout<< "invalid location";
        return NULL;
    }

    if (loc==1){
        if(list_length(head)>1){
            int val=pointer->data;
            int tempval=pointer->next->data;
            deleteat(head,2);
            pointer->data=tempval;
            return val;
        }
        else{
            head=NULL;
            return NULL;
        }
    }

    while (pointer->next != NULL){

        pointer2 = pointer->next;
        if(i==loc){                         //112 - 34 - 32 - 44
            int val = pointer2->data;
            pointer->next=pointer2->next;
            return val;
        }
        pointer=pointer2;
        i++;
    }
}


bool LinkedList:: insert(struct Node *&head,int value)
{

    //try{
        Node *q = new Node;
        q->data=value;
        q->next=NULL;
        if(head==NULL){
            head=q;
            return true;
        }
        Node *p=head;
        while(p->next!=NULL)
        {
            p=p->next;
        }
       p->next=q;
       return true;
    //}
    //catch(NullReferanceException * e ){
    //  cout<< "insertion was not successful" <<endl;
    //  return false;
    //}
}

bool LinkedList:: insertat(struct Node*&head, int value,int loc){
    Node *q = new Node;     //112 - 32- 44 
    q->data=value;
    if(loc>list_length(head)){
        insert(head,value);
        return true;
    }
    else if(loc<=0){
        cout<<"invalid location";
        return false;
    }

    else if(loc==1){
        q->next=head;
        head=q;
        return true;
    }
    else{
        int i=1;
        Node*p =head;
        while( i<loc-1){
            p=p->next;
            i++;
        }
        q->next=p->next;
        p->next=q;
        return true;
    }
}

void LinkedList:: display(struct Node *head){
    Node*p = head;
    while(p!=NULL){
        cout << p->data<< "  ";
        p=p->next;
    }
}

int main(){
    LinkedList my =new LinkedList();
    Node *head;
    Node *&ahead = *&head;
    my.init_list(ahead);
    my.display(head);
    my.insert(ahead,1111);
    //cout<<"1sr time";
    cout<< "length- " <<my.list_length(head)<<endl;
    //cout<< "deleting---  " <<deleteat(ahead,1)<<endl;
    my.insert(ahead,34);
    my.insert(ahead,32);
    my.insert(ahead,44);
    my.display(head);
    cout<<endl;
    my.insertat(ahead,4444,1);
    my.display(head);
    system("Pause");
    return 0;

}

2 个解决方案

#1

new LinkedList(); gives you a pointer to a LinkedList (i.e. LinkedList*). You cannot assign a LinkedList* to a LinkedList since a LinkedList* is not a LinkedList.

新LinkedList();给你一个指向LinkedList的指针(即LinkedList*)。由于LinkedList*不是LinkedList，所以不能将LinkedList*分配给LinkedList。

What you should probably do is LinkedList* my = new LinkedList;.

你应该做的是LinkedList* my = new LinkedList;

#2

So I found where the fault lied, and this is how it should have been -

所以我找到了错误所在，这就是它应该是怎样的。

int main(){
    LinkedList* my = new LinkedList;
    Node *head;
    my->start = head;
    Node *&ahead = *&head;
    my->init_list(ahead);
    my->display(head);
    my->insert(ahead,1111);
    //cout<<"1sr time";
    cout<< "length- " <<my->list_length(head)<<endl;
    //cout<< "deleting---  " <<deleteat(ahead,1)<<endl;
    my->insert(ahead,34);
    my->insert(ahead,32);
    my->insert(ahead,44);
    my->display(head);
    cout<<endl;
    my->insertat(ahead,4444,1);
    my->display(head);
    system("Pause");
    return 0;

}

#1