Question

我很难完成代码以完成以下步骤：

如何读取正整数文件（＆gt; 0）？
如何按升序排序创建双向链接的整数列表？
如何编写一个方法以升序或降序打印整个列表（输入参数'A'或'D'告诉打印方向）？
如果要添加的号码已经在列表中，或者如果他们要删除不在列表中的号码，则如果该号码不在列表中，如何通知用户。

运行程序时没有错误，只是尝试解决上述4个步骤。

这是我到目前为止所做的事情

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

using namespace std;
struct  node
{
    int number; 
    node *next; 
};
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);
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;
        numIntElement(x); 
        cout << " File exists \n";
        ////
        node * head = NULL;
        node *last = NULL;
        char choice;
        int number;
        do {
            choice = menu();
            switch (choice)
            {
            case '1':
                cout << " Please enter number : ";
                cin >> number;
                inser(head, last, number);
                break;
            case '2':
                remove(head, last);
            case '3':
                showlist(head);
                break;
            default:
                break;
            }
        } while (choice != '4');
        {

        }
    }

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

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

    while (!myfile.eof())
    {
        myfile >> n;
        countsingfie += n;
        if (countsingfie == 0) {
            cout << "Error : file exist but no data " << endl;
        }
        cout << "total number " << countsingfie << "\n" << endl;
        return countsingfie;
    }
}
bool isEmpty(node *head) {
    if (head == NULL) {
        return true; 
    }
    else
    {
        return false;
    }
}
char 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 insertAsFirstElement(node *&head, node *&last, int number) {
    node *temp = new node; 
    temp->number = number; 
    temp->next = NULL; 
    head = temp; 
    last = temp; 
}
void 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 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 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; 

        }
    }
}

如何按升序排序创建双向链接的整数列表？

0 个答案: