将对象传递给方法C ++

Question

Sorry for grammar, not a native speaker.

So I've got an assignment to create a simple program where you should be able to create three people, pass in their name, country, occupation and phone number. You should be able to print out saved information as a spreadsheet.

So I came up with this kind of piece of code:

#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;
        }
    }

}

Everything seem to work just fine. Except it doesn't change information in object's variables.

My guess is that when I pass a Person-type object to create_a_frankenstein(), method creates a copy of an object and starts working with a copy without changing anything in the original object.

I've tried to use pointer. I manage to do what I intend to on simplier examples:

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] << ' ';
    }
}

But when I try to use it in the Lab, it doesn't work as easily.

Will be glad to receive any advices on how to solve the problem and what topics I should brush up or look deeper in. Thank you in advance!

Answer 1

Try to pass your Person objects by reference. You can find more here: passing object by reference in C++ . Btw in your code example you don't call your function named 'first'.

Answer 2

The problem is on the void create_a_frankenstein(Person person) method.

You are passing a copy of the Person's object. If you want to keep the changes made to an object pass it as a reference: void create_a_frankenstein(Person& person)

Note:

1. Don't use arrays. Use std::vector instead if you want to store sequences of objects.

2. It would be nice if you define any getter member function as const --> return_type getter_name(params) const { //body here}