c++ - 这种控制 while() 循环的做法是好的吗？ C++

Question

我正在从事一个小型数据库项目。我已经用 switch() 函数创建了一个接口(interface)，它应该调用函数并循环直到我选择“EXIT”选项。我通过将指定值设置为 int Loop 变量来控制循环。以这种方式处理这种循环是一种好习惯吗？如果不是，那为什么？在其他函数中，当我有多个条件时，我什至两次使用那种变量。也许我应该做不同的事情？如果我在这种情况下使用 try()、throw()、catch() 异常是否有意义，那么它会是什么样子？这是我的一段代码:

void mainMenu() {

    vector<Employee> firmEmployees;
    vector<Intern> firmInterns;

    int Loop = 0;
    while (Loop == 0) {

        cout << endl << endl;
        cout << "================ EMPLOYEE DATABASE ================" << endl << endl;
        cout << " HIRE NEW EMPLOYEE (1)" << endl;
        cout << " MANAGE EMPLOYEES  (2)" << endl;
        cout << " HIRE NEW INTERN   (3)" << endl;
        cout << " MANAGE INTERNS    (4)" << endl;
        cout << " EXIT              (5)" << endl;
        cout << " Choose option... ";
        int option;
        cin >> option;

        if (option < 1 || option > 5 || !cin) {
            cout << endl << "---Wrong input!---";
            clearInput(); // cleaning cin
        } else {

            switch (option) {
                default:
                    break;
                case 1:
                    hireEmployee(firmEmployees);
                    break;
                case 2:
                    employeeMenu(firmEmployees);
                    break;
                case 3:
                    hireIntern(firmInterns);
                    break;
                case 4:
                    internMenu(firmInterns);
                    break;
                case 5:
                    Loop = 1;
                    break;
            }
        }
    }
}

编辑:另一个例子，更多变量。

void fireEmployee(vector<Employee>& sourceEmployee) {

    int repeat = 0;

    while (repeat == 0) {

        cout << "Enter ID to fire an employee: ";
        int id;
        cin >> id;

        if (cin.fail()) {
            clearInput();
            cout << "ID number needed!" << endl;
        } else {

            int buf = 0;

            for (auto &i : sourceEmployee) {

                if (i.getID() == id) {
                    i.Fire();
                    i.setSalary(0);
                    cout << i.getName() << " " << i.getSurname() << " (" << i.getID() << ") has been fired" << endl;
                    buf = 1;
                    repeat = 1;
                }
            }
            if (buf == 0) {
                cout << "No employee with ID: " << id << endl;

            }
        }
    }
}

Answer 1

最佳做法是将 while 循环提取到函数中并执行 return 而不是 Loop = 1;。那将是易于阅读和维护的显式流量控制。例如:

void mainMenuLoop(vector<Employee>& firmEmployees, vector<Intern>& firmInterns) {
    for(;;) {
        cout << "\n\n================ EMPLOYEE DATABASE ================\n\n";
        cout << " HIRE NEW EMPLOYEE (1)\n";
        cout << " MANAGE EMPLOYEES  (2)\n";
        cout << " HIRE NEW INTERN   (3)\n";
        cout << " MANAGE INTERNS    (4)\n";
        cout << " EXIT              (5)\n";
        cout << " Choose option... " << flush; // Must flush here.
        int option = -1; // Assign a wrong initial option.
        cin >> option;
        switch (option) {
            case 1:
                hireEmployee(firmEmployees);
                break;
            case 2:
                employeeMenu(firmEmployees);
                break;
            case 3:
                hireIntern(firmInterns);
                break;
            case 4:
                internMenu(firmInterns);
                break;
            case 5:
                return;
            default:
                cout << "\n---Wrong input!---" << endl;
                clearInput(); // cleaning cin
                break;
        }
    }
}

void mainMenu() {
    vector<Employee> firmEmployees;
    vector<Intern> firmInterns;
    mainMenuLoop(firmEmployees, firmInterns);
}

---

另请注意，在

int option;
cin >> option;

如果 cin >> option 失败 option 保留其原始不确定值，它可以是可用选项之一。为它分配一个不是有效选项的初始值更安全，例如 -1。