c++中的isExist

C++中没有名为isExist的函数或关键字。如果你想检查一个文件是否存在，你可以使用C++中的文件流库和操作系统的文件系统功能来实现。以下是一个简单的示例代码，用于检查文件是否存在：

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

bool fileExists(const std::string& filename)
{
    std::ifstream file(filename);
    return file.good();
}

int main()
{
    std::string filename = "test.txt";
    if (fileExists(filename))
    {
        std::cout << "File exists." << std::endl;
    }
    else
    {
        std::cout << "File does not exist." << std::endl;
    }
    return 0;
}

这个例子中，我们定义了一个名为fileExists的函数，它接受一个文件名并返回一个布尔值，表示文件是否存在。在main函数中，我们调用这个函数来检查文件是否存在，并打印相应的消息。

相关问题

c++职工管理系统

好的，下面是一个简单的职工管理系统的C++代码示例：

#include <iostream>
#include <cstring>

using namespace std;

// 员工类
class Employee {
public:
    Employee(int id, string name, int level) {
        this->m_Id = id;
        this->m_Name = name;
        this->m_Level = level;
    }

    // 显示员工信息
    void showInfo() {
        cout << "编号：" << this->m_Id << "\t姓名：" << this->m_Name << "\t级别：" << this->m_Level << endl;
    }

    // 获取级别
    int getLevel() {
        return this->m_Level;
    }

private:
    int m_Id;       // 编号
    string m_Name;  // 姓名
    int m_Level;    // 级别
};

// 职工管理类
class EmployeeManager {
public:
    EmployeeManager() {
        // 初始化员工数据
        Employee e1(10001, "张三", 1);
        Employee e2(10002, "李四", 2);
        Employee e3(10003, "王五", 3);

        // 添加到员工数组中
        this->m_EmpArray[0] = e1;
        this->m_EmpArray[1] = e2;
        this->m_EmpArray[2] = e3;

        // 设置员工数量
        this->m_EmpNum = 3;
    }

    // 显示菜单
    void showMenu() {
        cout << "********** 职工管理系统 **********" << endl;
        cout << "1. 增加职工" << endl;
        cout << "2. 显示职工" << endl;
        cout << "3. 删除职工" << endl;
        cout << "4. 修改职工" << endl;
        cout << "5. 查找职工" << endl;
        cout << "6. 排序职工" << endl;
        cout << "7. 清空文档" << endl;
        cout << "0. 退出系统" << endl;
        cout << endl;
    }

    // 增加职工
    void addEmployee() {
        int id;
        string name;
        int level;

        cout << "请输入员工编号：" << endl;
        cin >> id;
        cout << "请输入员工姓名：" << endl;
        cin >> name;
        cout << "请输入员工级别：" << endl;
        cin >> level;

        Employee e(id, name, level);
        this->m_EmpArray[this->m_EmpNum] = e;
        this->m_EmpNum++;

        cout << "增加成功！" << endl;
    }

    // 显示职工
    void showEmployee() {
        for (int i = 0; i < this->m_EmpNum; i++) {
            this->m_EmpArray[i].showInfo();
        }
    }

    // 根据编号查找职工
    int isExist(int id) {
        for (int i = 0; i < this->m_EmpNum; i++) {
            if (this->m_EmpArray[i].getLevel() == id) {
                return i;
            }
        }

        return -1;
    }

    // 删除职工
    void deleteEmployee() {
        int id;

        cout << "请输入要删除的员工编号：" << endl;
        cin >> id;

        int index = this->isExist(id);
        if (index != -1) {
            for (int i = index; i < this->m_EmpNum - 1; i++) {
                this->m_EmpArray[i] = this->m_EmpArray[i + 1];
            }

            this->m_EmpNum--;
            cout << "删除成功！" << endl;
        } else {
            cout << "删除失败，该员工不存在！" << endl;
        }
    }

    // 修改职工
    void modifyEmployee() {
        int id;
        string name;
        int level;

        cout << "请输入要修改的员工编号：" << endl;
        cin >> id;

        int index = this->isExist(id);
        if (index != -1) {
            cout << "请输入员工姓名：" << endl;
            cin >> name;
            cout << "请输入员工级别：" << endl;
            cin >> level;

            Employee &e = this->m_EmpArray[index];
            e = Employee(id, name, level);

            cout << "修改成功！" << endl;
        } else {
            cout << "修改失败，该员工不存在！" << endl;
        }
    }

    // 查找职工
    void findEmployee() {
        int id;

        cout << "请输入要查找的员工编号：" << endl;
        cin >> id;

        int index = this->isExist(id);
        if (index != -1) {
            this->m_EmpArray[index].showInfo();
        } else {
            cout << "查找失败，该员工不存在！" << endl;
        }
    }

    // 排序职工
    void sortEmployee() {
        for (int i = 0; i < this->m_EmpNum; i++) {
            for (int j = 0; j < this->m_EmpNum - i - 1; j++) {
                if (this->m_EmpArray[j].getLevel() > this->m_EmpArray[j + 1].getLevel()) {
                    Employee temp = this->m_EmpArray[j];
                    this->m_EmpArray[j] = this->m_EmpArray[j + 1];
                    this->m_EmpArray[j + 1] = temp;
                }
            }
        }

        cout << "排序成功！" << endl;
    }

    // 清空文档
    void clearDocument() {
        this->m_EmpNum = 0;
        cout << "清空成功！" << endl;
    }

    // 退出系统
    void exitSystem() {
        cout << "欢迎下次使用！" << endl;
        exit(0);
    }

private:
    Employee m_EmpArray[1000];  // 员工数组
    int m_EmpNum;               // 员工数量
};

int main() {
    EmployeeManager em;

    while (true) {
        em.showMenu();

        int choice;
        cin >> choice;

        switch (choice) {
            case 1:  // 增加职工
                em.addEmployee();
                break;
            case 2:  // 显示职工
                em.showEmployee();
                break;
            case 3:  // 删除职工
                em.deleteEmployee();
                break;
            case 4:  // 修改职工
                em.modifyEmployee();
                break;
            case 5:  // 查找职工
                em.findEmployee();
                break;
            case 6:  // 排序职工
                em.sortEmployee();
                break;
            case 7:  // 清空文档
                em.clearDocument();
                break;
            case 0:  // 退出系统
                em.exitSystem();
                break;
            default:
                break;
        }
    }

    return 0;
}

这个系统包含了增加职工、显示职工、删除职工、修改职工、查找职工、排序职工和清空文档等功能。可以根据需要进行扩展和修改。

图书馆管理系统C++

以下是一个简单的图书馆管理系统的C++代码，包括添加图书、删除图书、查找图书和修改图书等功能：

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

// 图书结构体
struct Book {
    string name;    // 书名
    double price;   // 价格
    int number;     // 编号
};

// 图书数组结构体
struct Arraybooks {
    Book *book;     // 图书数组指针
    int length;     // 图书数组长度
};

// 初始化图书数组
void initArray(Arraybooks *abs) {
    abs->book = new Book[100];
    abs->length = 0;
}

// 添加图书
void addBook(Arraybooks *abs) {
    cout << "请输入书名：" << endl;
    string name;
    cin >> name;
    cout << "请输入价格：" << endl;
    double price;
    cin >> price;
    cout << "请输入编号：" << endl;
    int number;
    cin >> number;
    abs->book[abs->length].name = name;
    abs->book[abs->length].price = price;
    abs->book[abs->length].number = number;
    abs->length++;
    cout << "添加成功！" << endl;
}

// 删除图书
void deleteBook(Arraybooks *abs) {
    cout << "请输入要删除的书名：" << endl;
    string name;
    cin >> name;
    int index = -1;
    for (int i = 0; i < abs->length; i++) {
        if (abs->book[i].name == name) {
            index = i;
            break;
        }
    }
    if (index == -1) {
        cout << "查无此书！" << endl;
    } else {
        for (int i = index; i < abs->length - 1; i++) {
            abs->book[i] = abs->book[i + 1];
        }
        abs->length--;
        cout << "删除成功！" << endl;
    }
}

// 查找图书
void findBook(Arraybooks *abs) {
    cout << "请输入要查找的书名：" << endl;
    string name;
    cin >> name;
    int index = -1;
    for (int i = 0; i < abs->length; i++) {
        if (abs->book[i].name == name) {
            index = i;
            break;
        }
    }
    if (index == -1) {
        cout << "查无此书！" << endl;
    } else {
        cout << "书名为：" << abs->book[index].name << "\t";
        cout << "价格为：" << abs->book[index].price << "\t";
        cout << "编号为：" << abs->book[index].number << endl;
    }
}

// 修改图书
void modifyBook(Arraybooks *abs) {
    cout << "请输入要修改的书名：" << endl;
    string name;
    cin >> name;
    int index = -1;
    for (int i = 0; i < abs->length; i++) {
        if (abs->book[i].name == name) {
            index = i;
            break;
        }
    }
    if (index == -1) {
        cout << "查无此书！" << endl;
    } else {
        cout << "请输入新的书名：" << endl;
        string newName;
        cin >> newName;
        cout << "请输入新的价格：" << endl;
        double newPrice;
        cin >> newPrice;
        cout << "请输入新的编号：" << endl;
        int newNumber;
        cin >> newNumber;
        abs->book[index].name = newName;
        abs->book[index].price = newPrice;
        abs->book[index].number = newNumber;
        cout << "修改成功！" << endl;
    }
}

// 显示图书
void showBooks(Arraybooks *abs) {
    if (abs->length == 0) {
        cout << "书架为空" << endl;
    } else {
        for (int i = 0; i < abs->length; ++i) {
            cout << "书籍名字 ： " << abs->book[i].name << "\t";
            cout << "书籍价格 ： " << abs->book[i].price << "\t";
            cout << "书籍编号 ： " << abs->book[i].number << endl;
        }
    }
}

// 判断图书是否存在
int isExist(Arraybooks *abs, string name) {
    int index = -1;
    for (int i = 0; i < abs->length; i++) {
        if (abs->book[i].name == name) {
            index = i;
            break;
        }
    }
    return index;
}

int main() {
    Arraybooks abs;
    initArray(&abs);
    while (true) {
        cout << "请选择操作：" << endl;
        cout << "1.添加图书" << endl;
        cout << "2.删除图书" << endl;
        cout << "3.查找图书" << endl;
        cout << "4.修改图书" << endl;
        cout << "5.显示图书" << endl;
        cout << "6.退出" << endl;
        int choice;
        cin >> choice;
        switch (choice) {
            case 1:
                addBook(&abs);
                break;
            case 2:
                deleteBook(&abs);
                break;
            case 3:
                findBook(&abs);
                break;
            case 4:
                modifyBook(&abs);
                break;
            case 5:
                showBooks(&abs);
                break;
            case 6:
                return 0;
            default:
                cout << "输入有误，请重新输入！" << endl;
                break;
        }
    }
    return 0;
}