Question

我必须设计一个程序，允许用户在双向链表中输入5个节点的信息，然后按字母顺序对双向链表进行排序。它跳过允许用户输入地址，不打印除名称之外的任何信息，并且不按字母顺序对列表进行排序。我做错了什么？

#include <iostream>
#include <string>

struct node
{
    std::string firstName;
    std::string lastName;
    std::string address;
    long phoneNum;
    node *next;
    node *prev;
};

bool isEmpty(node *head);
void insertAsFirstElement(node *&head, node *&last, std::string firstName, std::string lastName, std::string address, long phoneNum);
void insert(node *&head, node *&last, std::string firstName, std::string lastName, std::string address, long phoneNum);
void searchFor(node *&last, std::string lastName);
void showList(node *current);


bool isEmpty(node *head)
{
    if(head == NULL)
        return true;
    else
        return false;
}


void insertAsFirstElement(node *&head, node *&last, std::string firstName, std::string lastName, std::string address, long phoneNum)
{
    node *temp = new node;
    temp->firstName = firstName;
    temp->lastName = lastName;
    temp->address = address;
    temp->phoneNum;
    temp->next = NULL;
    temp->prev = NULL;
    head = temp;
    last = temp;
}

void insert(node *&head, node *&last, std::string firstName, std::string lastName, std::string address, long phoneNum)
{

    if(isEmpty(head))

        insertAsFirstElement(head, last, firstName, lastName, address, phoneNum);

    else
    {
        node *temp = new node;
        temp->firstName = firstName;
        temp->lastName = lastName;
        temp->address = address;
        temp->phoneNum;

        int result = lastName.compare(last->lastName);

        if (result < 0)
        {
            temp->next = head;
            head->prev = temp;
            temp->prev = NULL;
            head = temp;
        }

        else if ( result > 0)
        {
            temp->next = NULL;
            temp->prev = last;
            last->next = temp;
            last = temp;
        }

    }

}

void searchFor(node *&last, std::string findName)
{
    node *temp = last;
    while (temp != NULL)
    {
        if (temp->lastName == findName)
        {
            std::cout << temp->firstName << " " << temp->lastName << " " << temp->address << " " << temp->phoneNum << std::endl;;
        }

        temp = temp->prev;
    }
}


void showList(node *current)
{
    if(isEmpty(current))
        std::cout << "The list is empty\n";
    else
    {
        std::cout << "The list contains: \n";
        while(current != NULL)
        {
            std::cout << current->firstName << " " << current->lastName << " " << current->address << " " << current->phoneNum << std::endl;
            current = current->next;
        }
     } 
}

int main()
{
    node *head = NULL;
    node *last = NULL;
    std::string firstName;
    std::string lastName;
    std::string address;
    long phoneNum;

    int count;
    count = 5;
    while (count > 0)
    {
        std::cout << "Enter the first name of person #" << count << ":\n";
        std::cin >> firstName;
        std::cout << "Enter the last name of person #" << count << ":\n";
        std::cin >> lastName;
        std::cout << "Enter the address of person #" << count << ":\n";
        std::getline(std::cin,address);
        std::cout << "Enter the phone number of person #" << count << ":\n";
        std::cin >> phoneNum;
        insert(head, last, firstName, lastName, address, phoneNum);
        count = count - 1;
     } 

    showList(head);

    std::string findName;
    std::cout << "What is the last name of the person you would like to find?\n";
    std::cin >> findName;

    searchFor(last, findName);

    return 0; 

}

Answer 1

您的问题是，您混合使用cin >>和getline，这在C ++中存在问题，原因是跟踪新行，而不是。

好的做法是始终使用getline，然后使用stringstream将行拆分为令牌。例如，我将您的解决方案修改为仅使用getline和字符串流（注意：您需要在文件顶部#include <sstream>。

您可以详细了解混合cin >>和getline的问题以及解决问题的其他方法here。

int main()
{
    node *head = NULL;
    node *last = NULL;
    std::string firstName;
    std::string lastName;
    std::string address;
    std::string phoneNumStr;
    long phoneNum;

    int count;
    count = 5;
    while (count > 0)
    {
        std::cout << "Enter the first name of person #" << count << ":\n";
        std::getline(std::cin,firstName);   // no use of cin >>
        std::cout << "Enter the last name of person #" << count << ":\n";
        std::getline(std::cin,lastName);    // no use of cin >>
        std::cout << "Enter the address of person #" << count << ":\n";
        std::getline(std::cin,address);
        std::cout << "Enter the phone number of person #" << count << ":\n";
        std::getline(std::cin,phoneNumStr);
        std::stringstream s(phoneNumStr);    // no use of cin. Using stringstream to break up line and extract it into phoneNum
        s >> phoneNum;
        insert(head, last, firstName, lastName, address, phoneNum);
        count = count - 1;
     }

    showList(head);

    std::string findName;
    std::cout << "What is the last name of the person you would like to find?\n";
    std::cin >> findName;

    searchFor(last, findName);

    return 0;
}

程序跳过std :: getline

1 个答案: