我如何在将我的类分成 ah 和 .cpp 文件时使用聚合？

Question

Context

My professor gave me a task to make a program using aggregation between 2 classes while also separating the classes into a .h and .cpp files.

My solution

The header file containing the class declaration:

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

class medicalCompany {
private:
    string ceoName;
    string email;
    string phoneNumber;
    string locate;
public:
    medicalCompany();
    void Name(string n);
    void mail(string m);
    void phone(string p);
    void location(string l);
    ~medicalCompany();

};
class origin {
private:
    medicalCompany country;
    
public:
    origin();
    void address();
    ~origin();

};

and my.cpp file:

#include <iostream>
#include "function.h"
#include <string>
using namespace std;
medicalCompany::medicalCompany() {
    cout << "OUR COMPANY IS GLAD TO BE OF SERVICE !" << endl;
    cout << "****************************************************" << endl;
}
void medicalCompany::Name(string n){
    ceoName = n;
    cout << "OUR CEO IS " << endl;
    cout<< ceoName << endl;
    cout << "****************************************************" << endl;
}
void medicalCompany::mail(string m) {
    email = m;
    cout << "USE OUR EMAIL TO CONTACT US : " << endl;
    cout<< email << endl;
    cout << "****************************************************" << endl;
}
void medicalCompany::phone(string p) {
    phoneNumber = p;
    cout << "THIS IS OUR CUSTOMER SERVICE PHONE NUMBER " << endl;
    cout<< phoneNumber << endl;
    cout << "****************************************************" << endl;
}
void medicalCompany::location(string l) {
    locate = l;
    cout << " OUR COMPANY IS LOCATED IN " << endl;
    cout << locate << endl;
    cout << "****************************************************" << endl;
}
medicalCompany::~medicalCompany() {
    cout << "thanks for trusting our company ^_^" << endl;
    cout << "****************************************************" << endl;
}
origin::origin() {
    cout<< "constructor 2"<<endl;
}
void origin::address() {
    cout << country.location;
}
origin::~origin() {
    cout << "bye" << endl;
}

The two classes are used in my main.cpp file:

#include <iostream>
#include <string>
#include "function.h"
using namespace std;

int main() {

    medicalCompany o;
    o.Name("jack");
    o.mail("ouremail@company.com");
    o.phone("2342352134");
    o.location("Germany");
    origin o2;

    return 0;
}

Problem

I run into this error:

Severity Code Description Project File Line Suppression State
Error   C3867 'medicalCompany::location': non-standard syntax; use '&' to create a pointer to member    CP2_HW  c:\function.cpp 41 

Answer 1

You can either:

• replace void origin::address(){cout << country.location;} by void origin::address(){country.location();}

• or by void origin::address(){cout << country.locate;} if you put the locate member as a public variable.

Also, few remarks:

• Generally you would prefer avoiding exposing private members, so the first solution should be prefered.

• the instruction using namespace std; is usually considered bad practice, and should be avoided, as the cost of possible risks does not overweight the benefit of not having to type std::cout (see this question for more information)

• In terms of naming convention, I would have exchanged the names of locate and location : location should be the member variable and locate the action (function) of getting the location.

• Prefer using a constructor and intialization lists rather than getter/setter.

• Your output formatting should be very separate from the logic of your classes, for example implementing a << operator for your class.

Following this logic, your code should look more like:

#include <iostream>
#include <string>

class medicalCompany {
private:
  std::string _ceoName;
  std::string _email;
  std::string _phoneNumber;
  std::string _location;
public:
  
  // Constructor
  medicalCompany(std::string name, std::string email, std::string phone, std::string location):
  _ceoName(name), 
  _email(email), 
  _phoneNumber(phone), 
  _location(location)
  {}
  friend ostream& operator<<(ostream& os, const medicalCompany& dt);
  };

and for the ostream operator:

ostream& operator<<(ostream& os, const medicalCompany& co)
{
    os << co._ceoName << " " co._phoneNumber << ' ' << co._email;
    return os;
}

This would allows to write code like this in your main:

int main() {
  medicalCompany o("jack", "ouremail@company.com","2342352134","Germany")
  std::cout << o << std::endl;   
  return 0;
}

The code is not functional and you would have to edit it to fit your formating requirement, but you have the idea:) Good luck!