Question

这个程序将显示文本文件

中的整数

1 2 3 4 5 6

并要求用户

添加数字“
从列表中删除号码
显示列表。

有人可以帮助我实施以下步骤：

1.如何将文本文件中的整数插入到双向链表中。

2.如果用户添加了数字，则应将该数字添加到文本文件中。

3-如果用户删除号码，则应从文本文件中删除该号码。

#include <iostream>
#include <string>
#include <fstream>

using namespace std;
struct  node
{
    int number; 
    node *next; 
    node *prev; 
}*start;

class double_llist
{
public:
    bool isEmpty(node *head);
    char menu();
    void insertAsFirstElement(node *&head, node *&last, int number);
    void inser(node*&head, node*&last, int number);
    void remove(node *&head, node *&last);
    void showlist(node *current);
    int numIntElement(ifstream&x);
private:

};

int main() {

    string filename;
    cout << " Please enter the name of the file = "; 
    cin >> filename; 
    ifstream myfile; 
    myfile.open(filename); 
    if (!myfile.is_open()) {
        cout << endl << " failed to open file, check that it exists and you have access \n" << "\n" << endl; 

    }
    else if (myfile.is_open())
    {
        ifstream x;
        double_llist dl;
        dl.numIntElement(x); 
        int int1 = 0; 
        cout << " File exists \n";

        ////
        node * head = NULL;
        node *last = NULL;
        char choice;
        int number;
        do {
            choice = dl.menu();
            switch (choice)
            {
            case '1':
                cout << " Please enter number : ";
                cin >> number;
                dl.inser(head, last, number);
                break;
            case '2':
                dl.remove(head, last);
            case '3':
                dl.showlist(head);
                break;
            default:
                break;
            }
        } while (choice != '4');
        {

        }
    }

    system("pause");
    return 0; 
}
int double_llist::numIntElement(ifstream&x) {

    int n = 0;
    int m; 
    ifstream myfile("file.txt");
    int countsingfie = 0;

    while (!myfile.eof())
    {
        myfile >> n;
        //if (countsingfie == 0) {
        //  cout << "Error : file exist but no data " << endl;
        //}
        cout << "The numbers in the file are  " << n<< "" << endl;
    }
    return countsingfie;
}
bool double_llist::isEmpty(node *head) {
    if (head == NULL) {
        return true; 
    }
    else
    {
        return false;
    }
}
char double_llist::menu() {
    char choice; 
    cout << " Main Menu \n"; 
    cout << " 1 . Add a number \n";
    cout << " 2 . Delete a number from the list \n";
    cout << " 3 . Show the list \n"; 
    cout << " 4.  Exit \n";
    cin >> choice; 
    return choice;
}
void  double_llist::insertAsFirstElement(node *&head, node *&last, int number) {
    node *temp = new node; 
    temp->number = number; 
    temp->next = NULL; 
    head = temp; 
    last = temp; 
}
void double_llist::inser(node*&head, node*&last, int number) {
    if (isEmpty(head)>0){
        insertAsFirstElement(head, last, number); 
    }
    else if (isEmpty(head) < 0)
    {
        cout << " Please enter a number above 0 " << endl;
    }
    else
    {
        node *temp = new node;
        temp->number = number;
        temp->next = NULL;
        last->next = temp;
        last = temp;
    }
}
void  double_llist::remove(node *&head, node *&last) {
    if (isEmpty(head)) {
        cout << " Sorry, The list is already empty \n"; 

    }
    else if (head == last)
    { 
        delete head; 
        head = NULL;
        last = NULL; 

    }
    else
    {
        node *temp = head; 
        head = head->next; 
        delete temp; 
    }
}
void double_llist::showlist(node *current) {

    if (isEmpty(current)) {
        cout << " The list is empty \n";
    }
    else
    {
        cout << " The list contains: \n "; 
        while (current != NULL)
        {
            cout << current->number << endl; 
            current = current->next; 

        }
    }
}

如何将整数编号插入文本文件中的双向链表？

0 个答案: