Question

我是C ++的新手，目前正在试验链接列表，但我在程序中显示多个值时遇到了麻烦。问题出在DisplayAll函数中。

    struct node
    {
        string firstname;
        string lastname;
        string phonenumber;
        string dayofbirth;
        string monthofbirth;
        string yearofbirth;
        string age;
        string streetname;
        string city;
        string state;
        string zipcode;
        char ch;
        static int count;
        int count2;
        node* next;
    };

    class InfoBook
    {
    private:
        node* head;
        node* current;
        node* temp;

    public:
        InfoBook();

        void userPromptStatement();
        node* AddNode(node*);
        void DisplayAll();
        //node* SearchNode();
        //void sort(node*, int);
        void UpdateNode();
        //node* DeleteNode(node*);
    };

node* InfoBook::AddNode(nodePtr temp)
{ 
    string firstname;
    string lastname;
    string phonenumber;
    string dayofbirth;
    string monthofbirth;
    string yearofbirth;
    string age;
    string streetname;
    string city;
    string state;
    string zipcode;
    InfoBook ad;

       if(head != NULL)
        {
            current = head;
            while(current -> next != NULL)
            {
                current = current -> next;
            }
            current -> next = new node;
            current -> firstname = temp -> firstname;
            current -> lastname = temp -> lastname;
                     ////code here to add the other values////
            current -> zipcode = temp -> zipcode;
            current -> next -> next = nullptr;
            return current;
            ad.userPromptStatement();
        }
       else
        {
            head = new node;
            head -> firstname = temp -> firstname;
            head -> lastname = temp -> lastname;
                    ////code here to add the other values////
            head -> zipcode = temp -> zipcode;
            head -> next = nullptr;
            return current;
        }
}

    ////////////////////////////////DisplayAll/////////////////////////////////

    void InfoBook::DisplayAll()
    {
        current = head;
        int count = 1;
        string firstname;
        string lastname;
        string phonenumber;
        string dayofbirth;
        string monthofbirth;
        string yearofbirth;
        string age;
        string streetname;
        string city;
        string state;
        string zipcode;

            if(current == nullptr)
            {
                cout << "\n\n\No Record exists.";
            }
                while(current != NULL)
                {      ////////The problem is somewhere between here////////
                    cout << "Record # " << count << " : ";
                    cout << current -> firstname << endl;
                    cout << current -> lastname << endl;
                    cout << current -> phonenumber << endl;
                    cout << current -> dayofbirth << endl;
                    cout << current -> monthofbirth << endl;
                    cout << current -> yearofbirth << endl;
                    cout << current -> age << endl;
                    cout << current -> streetname << endl;
                    cout << current -> city << endl;
                    cout << current -> state << endl;
                    cout << current -> zipcode << endl;
                    cout <<"\n\n\n";
                    current = current -> next;
                    count++;
                }
    }
                            ///////////////////////////////////////////////

程序仅显示“记录＃：”，但不显示值。有什么想法吗？

//////////////////added//////////////////////
 node* temp = new node;
 node* current;
 char ch;
 int count2 = 0;
 ad.userPromptStatement();

 while(1)
 {
    cin >> ch;
    switch(ch)
    {
        case '1':
            system("cls");
            cout << "\n\nINSERT RECORD";
                        cout << "\n\nInput FIRST NAME: ";
                        cin.ignore();
                        getline(cin,firstname,'\n');

                        cout << "\nRecord inserted!";
                    current = ad.AddNode(temp);
                ad.userPromptStatement();
        break;

        case '2':
            system("cls");
            cout << "\n\nDISPLAY ALL\n\n";
            ad.DisplayAll();
            _getch();
            ad.userPromptStatement();
        break;

Answer 1

可能出现的问题是：

current -> next = new node;
current -> firstname = temp -> firstname;
current -> lastname = temp -> lastname;
        ////code here to add the other values////
current -> zipcode = temp -> zipcode;

在上面的代码中，您在current->next分配了一个新节点，但是分配到current的字段。

另一个问题是您实际上没有初始化您在AddNode调用中使用的节点结构中的字段。

Answer 2

如果您想使用链接列表，我建议您不要重新发明轮子而是使用的std ::名单。使用std :: list时，您仍然可以挽救大部分节点类。

#include <list>
#include <string>

using namespace std;

struct node
{
    string firstname;
    string lastname;
    string phonenumber;
    string dayofbirth;
    string monthofbirth;
    string yearofbirth;
    string age;
    string streetname;
    string city;
    string state;
    string zipcode;
    char ch;
};

typedef std::list<node> NodeList;

class InfoBook
{
    NodeList nList;

    public:
        InfoBook();

        void userPromptStatement();
        void AddNode(node& theNode) { nList.push_back(theNode); }
        void DisplayAll();
};

void InfoBook::DisplayAll()
{
    NodeList::iterator it = nList.begin();
    while (it != nList.end())
    {
        node& curNode = *it;
        // now print out curNode in whatever way you see fit
        // ...
        ++it;  // go to nest node in the list
    }
}

注意代码的缩短程度，尤其是AddNode（）函数。节点类不再需要保留事物的数量，因为nList.size（）将为您提供节点数。

上面的示例向您介绍了标准库容器（std :: list）和迭代器（DisplayAll函数中的“it”）。我没有填写其他InfoBook功能，因为我会留给你做这个，但希望你能得到关于如何完成的想法。

C ++链接列表全部显示

2 个答案: