C++程序仅读取文件前7行，排查代码异常问题求助

我写了一段C++代码，定义了Employee、Node、LinkedList类，通过readFile函数读取员工数据文件，将数据存入链表并排序后展示。但在多个编译器中，程序仅输出文件中的7行数据，而文件实际包含更多行。逻辑和语法上看似没问题，一开始怀疑是编译器问题，现在觉得代码可能存在错误，尤其是readFile函数或者链表插入逻辑，请求帮忙排查原因。

代码实现 #

#include <iostream>
#include <string> 
#include <sstream>
#include <fstream>
using namespace std;

class Employee { // employee class
public:
    int employeeId;
    string firstName;
    string lastName;
    string phoneNumber;
    string emailAddress;
    double salary;

    Employee(int id, string first, string last, string phone, string email, double sal)             // employee class constructor 
        :employeeId(id), firstName(first), lastName(last), phoneNumber(phone), emailAddress(email), salary(sal) {}

    void display() { // used to display an object of the employee class
        cout << "Id: " << employeeId << ", Name: " << firstName << " " << lastName
            << ", Phone Number: " << phoneNumber << ", Email: " << emailAddress
            << ", Salary: " << salary << endl;
    }
};


class Node { // class for each node of the linked list 
public:
    Employee* info;
    Node* next;

    Node(Employee* emp) : info(emp), next(nullptr) {}
};

class LinkedList { //the link list class itself 
private:
    Node* head;
public:
    LinkedList() : head(nullptr) {} // constructopr that initializes the list with no contents (empty)

    void insert(Employee* emp) {
        Node* newNode = new Node(emp);
        if (head == nullptr || head->info->employeeId >= newNode->info->employeeId) {
            newNode->next = head;
            head = newNode;
        }
        else {
            Node* current = head;
            while (current->next != nullptr && current->next->info->employeeId < newNode->info->employeeId) {
                current = current->next;
            }
            newNode->next = current->next;
            current = current->next;

        }
    }


    void display() { // function that displays the nodes of the link list 
        Node* current = head;
        while (current != nullptr) {
            current->info-> display();
            current = current->next;
        }
    }

    ~LinkedList() {
        Node* current = head;
        while (current != nullptr) {
            Node* next = current->next;
            delete current;
            current = next;
        }
    }
};

// Now that all three classes are created and the functions needed with them, 
// we can now read from the file and add the employees to the linked list 
void readFile(const string& filename, LinkedList& list) {
    ifstream file(filename);
    if (!file.is_open()) {
        cerr << "Error opening file: " << filename << endl;
        return;
    }

    string line;
    while (getline(file, line)) {
        stringstream ss(line);
        int id;
        string firstName, lastName, phoneNumber, emailAddress;
        double salary;
        ss >> id >> firstName >> lastName >> phoneNumber >> emailAddress >> salary;
        Employee* emp = new Employee(id, firstName, lastName, phoneNumber, emailAddress, salary);
        list.insert(emp);
    }
    file.close();
}
int main() {
    LinkedList list;
    readFile("Week 1-employeeDataset_Project 1.txt", list);
    list.display();
    return 0;
}

文件示例数据 #

文件中一行示例数据如下：

12690 Glynis Filipson 539-917-2209 gfilipson56@liveinternet.ru 105401.55

问题根源及修复方案 #

1. 链表插入函数的致命错误 #

LinkedList::insert函数的else分支存在逻辑错误：找到合适的插入位置后，代码执行了current = current->next;，这一步完全没有完成插入操作，只是移动了指针，导致新节点根本没有被链接到链表中。只有当节点被插入到链表头部时（if分支）才会成功，其他节点全部丢失，这就是为什么只显示少数行的原因。

修正后的insert函数代码：

void insert(Employee* emp) {
    Node* newNode = new Node(emp);
    if (head == nullptr || head->info->employeeId >= newNode->info->employeeId) {
        newNode->next = head;
        head = newNode;
    }
    else {
        Node* current = head;
        while (current->next != nullptr && current->next->info->employeeId < newNode->info->employeeId) {
            current = current->next;
        }
        newNode->next = current->next;
        current->next = newNode; // 正确的插入操作，将新节点链接到链表中
    }
}

2. 文件读取的错误处理缺失 #

当前readFile函数没有检查数据读取是否成功，如果某一行数据格式不符合预期（比如薪资不是数字、字段缺失），ss >> ...会失败，但代码仍会创建无效的Employee对象，甚至可能导致后续的getline因为流状态异常而停止读取。

添加读取校验的修正代码：

void readFile(const string& filename, LinkedList& list) {
    ifstream file(filename);
    if (!file.is_open()) {
        cerr << "Error opening file: " << filename << endl;
        return;
    }

    string line;
    while (getline(file, line)) {
        stringstream ss(line);
        int id;
        string firstName, lastName, phoneNumber, emailAddress;
        double salary;
        // 检查所有字段是否读取成功
        if (ss >> id >> firstName >> lastName >> phoneNumber >> emailAddress >> salary) {
            Employee* emp = new Employee(id, firstName, lastName, phoneNumber, emailAddress, salary);
            list.insert(emp);
        } else {
            cerr << "无效的行格式，跳过该行: " << line << endl;
        }
    }
    file.close();
}

3. 内存泄漏问题 #

原LinkedList的析构函数只删除了Node对象，但没有删除Node中指向的Employee对象，会导致内存泄漏。需要在析构时同时释放Employee的内存。

修正后的析构函数：

~LinkedList() {
    Node* current = head;
    while (current != nullptr) {
        Node* next = current->next;
        delete current->info; // 释放Employee对象
        delete current;
        current = next;
    }
}

内容的提问来源于stack exchange，提问作者Kevin Lando