Question

对不起语法，不是母语人士。

所以我已经完成了创建一个简单程序的任务，你应该可以创建三个人，传递他们的姓名，国家，职业和电话号码。您应该能够将保存的信息打印为电子表格。

所以我想出了这样一段代码：

#include <iostream>
#include <iomanip>

using namespace std;

class Person {
public:
    string surname;
    string name;
    string country;
    string occupation;
    string phone;

    // Set default value
    Person() {
        surname = "empty";
        name = "empty";
        country = "empty";
        occupation = "empty";
        phone = "empty";
    }

    // SET PERSON'S DATA
    void set_surname(string entered_surname) {
        surname = entered_surname;
    }

    void set_name(string entered_name) {
        name = entered_name;
    }

    void set_country(string entered_country) {
        country = entered_country;
    }

    void set_occupation(string entered_occupation) {
        occupation = entered_occupation;
    }

    void set_phone(string entered_phone) {
        phone = entered_phone;
    }

    // RETURN PERSONS DATA
    string get_surname() {
        return surname;
    }
    string get_name() {
        return name;
    }
    string get_country() {
        return country;
    }
    string get_occupation() {
        return occupation;
    }
    string get_phone() {
        return phone;
    }

};

void create_a_frankenstein(Person person) {
    string entered_data;
    cout << "Please, enter person's surname: \n";
    cin >> entered_data;
    person.set_surname(entered_data);

    cout << "Please, enter person's name: \n";
    cin >> entered_data;
    person.set_name(entered_data);

    cout << "Please, enter person's country: \n";
    cin >> entered_data;
    person.set_country(entered_data);

    cout << "Please, enter person's occupation: \n";
    cin >> entered_data;
    person.set_occupation(entered_data);

    cout << "Please, enter person's phone: \n";
    cin >> entered_data;
    person.set_phone(entered_data);
}

int main() {

    Person fst;
    Person snd;
    Person trd;
    Person group[3] = {fst, snd, trd};

    int people_created = 0;

    bool switch_on = true;

    while (switch_on) {
        cout << "What operation would you like to perform: \n";
        cout << "    1) Create new person \n";
        cout << "    2) Print out all of the available information \n";
        cout << "    3) Quit \n";


        //Get the number of operation to perform
        int operation;
        cout << "Please, enter a number: \n";
        cin >> operation;

        switch (operation) {
        //Option 1: create a person
        case 1:
            if (people_created == 3) {
                cout << "It is not possible to create more that three people";
            }

        else {
                create_a_frankenstein(group[people_created]);
                people_created++;
            }
            break;

        //Option 2: print out all of the available information
        case 2:
            for (int i = 0; i < 3; i++) cout << setw(20) << setfill(' ') << left << group[i].get_surname();
            for (int i = 0; i < 3; i++) cout << setw(20) << setfill(' ') << left << group[i].get_name();
            for (int i = 0; i < 3; i++) cout << setw(20) << setfill(' ') << left << group[i].get_country();
            for (int i = 0; i < 3; i++) cout << setw(20) << setfill(' ') << left << group[i].get_occupation();
            for (int i = 0; i < 3; i++) cout << setw(20) << setfill(' ') << left << group[i].get_phone();
            break;

        // Option 3: quit
        case 3:
            switch_on = false;
            break;
        }
    }

}

一切似乎都很好。除了它不会改变对象变量中的信息。

我的猜测是，当我将Person类型对象传递给create_a_frankenstein（）时，方法会创建一个对象的副本，并开始使用副本而不更改原始对象中的任何内容。

我试过用指针。我设法在简单的例子上做我想做的事情：

void first(int* a){
    for (int i = 0; i < 7; i++) {
        a[i] = a[i]+1;
    }
}

int main() {
    int a[7] = {0, 1, 2, 3, 4, 5, 6};
    for (int i=0; i<7; i++) {
        cout << a[i] << ' ';
    }
}

但是当我尝试在实验室中使用它时，它并不容易。

很高兴收到有关如何解决问题的建议，以及我应该深入了解或深入了解的主题。提前谢谢！

Answer 1

Try to pass your Person objects by reference. You can find more here: passing object by reference in C++。在您的代码示例中，您不要将名为“first”的函数调用。

Answer 2

问题出在void create_a_frankenstein(Person person)方法上。

您正在传递Person对象的副本。如果要保持对对象所做的更改将其作为参考传递：void create_a_frankenstein(Person& person)

注意：

不要使用数组。如果要存储对象序列，请使用std::vector。
如果您将getter member function定义为const - ＆gt;那就太好了。 return_type getter_name(params) const { //body here}

将对象传递给方法C ++

2 个答案: