Default constructor error no matching function for call to - c++

Question

In main(), I am making an array myAppointments, and realize to make it work I would need to create a default constructor in Appointments.h, but when I do I get this error:
no matching function for call to 'Time::Time()'
Appointment(){
Here is Main:
/*
* Homework 4 -- UPDATE as needed
*/
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include "Appointment.h"
using namespace std;
void callPrint (Time &TimeOrApptObject) { TimeOrApptObject.print(); }
int main(){
int month, day, year, hour, minute,howLong;
Appointment myAppointments[19];
ifstream HW4DataFileHandle;
HW4DataFileHandle.open("Lab6Data.txt");
while (!HW4DataFileHandle.eof( )) {
for (int i = 1; i < 20; i++) {
HW4DataFileHandle>>month;
HW4DataFileHandle>>day;
HW4DataFileHandle>>year;
HW4DataFileHandle>>hour;
HW4DataFileHandle>>minute;
HW4DataFileHandle>>howLong;
myAppointments[i] = Appointment( month, day, year, hour, minute, howLong);
}
cout <<"enter a month" <<endl;
cin >> month;
cout <<"enter a day" <<endl;
cin >> day;
cout <<"enter a year"<<endl;
cin >> year;
Date myDate( month, day, year);
cout <<"Appointments for" << month <<"/" << day <<"/" << year <<":"<< endl;
for (int i = 0; i <13; i++){
if ( myAppointments[i]==Date myDate )
{
Time thisTime = myAppointments[i];
thisDate.print();
cout << endl;
}
}
}
And here are the header files:
Date.H
// Date.h -- Class Date UPDATE as needed
#ifndef DATE_H
#define DATE_H
class Date {
private:
int month;
int day;
int year;
public:
Date(int m, int d, int y) : month(m), day(d), year(y)
{
}
friend bool friendTorCompare2Dates (const Date&,const Date& );
};
bool friendTorCompare2Dates (const Date& Right, const Date& Left)
{
if (Right.month == Left.month && Right.day == Left.day )
return true;
else
return false;
}
#endif
Time.H
//Time.h -- Class Time UPDATE as needed
using namespace std;
#include<iostream>
#ifndef TIME_H
#define TIME_H
class Time {
private :
int hour; int minute;
public:
Time(int h, int m) : hour(h)
{
}
virtual void print() {
cout << hour << " " << minute <<" " ;
}
};
#endif
Appointment.h
// Appointment.h -- Class Appointment UPDATE as needed
//
using namespace std;
#include "Time.h"
#include "Date.h"
#ifndef APPOINTMENT_H
#define APPOINTMENT_H
class Appointment: public Date, public Time {
private:
int howLong;
public:
Appointment(int month, int day, int year, int hour, int minute, int howLong) :
Date(month, day, year), Time(hour, minute), howLong(howLong)
{
}
Appointment(){
month;
day;
year;
hour;
minute;
howLong;
}
};
#endif
What do I need to change in order to have my default constructor in Appointment work? If you notice any thing else, or have any other questions in regards to my question, please let me know. I would appreciate it if you would include an example in your answer.

Answer 1

This line:
Appointment myAppointments[19];
will call the default constructor of Appointment for each element.
Your default constructor doesn't explicitly call a constructor of Time, so the default constructor of Time will be called, which doesn't exist. Same with Date.
You can reinstate the default constructor like this:
class Time {
// ...
public:
Time() = default;
};
To get reasonable default behavior, you should provide default initial values for the members of your class, e.g.
class Time {
private :
int hour = 0;
int minute = 0;
public:
// ...
};

Answer 2

When you declare the array Appointment myAppointments[19];, the default constructor for Appointment is used immediately for all 19 elements. However, Date and Time do not have default constructors defined, but Appointment's default constructor will try to call them both implicitly, hence the error you are seeing since they don't exist.
So, you have 4 different ways to fix this:
make Appointment's default constructor call Date's and Time's non-default constructors explicitly (just like your other Appointment constructor does), passing in default values to them:
Appointment() :
Date(0, 0, 0), Time(0, 0), howLong(0)
{
}
give Date and Time their own default constructors, eg:
class Date {
private:
int month;
int day;
int year;
public:
Date() : month(0), day(0), year(0)
{
}
Date(int m, int d, int y) : month(m), day(d), year(y)
{
}
...
};
class Time {
private :
int hour;
int minute;
public:
Time() : hour(0), minute(0)
{
}
Time(int h, int m) : hour(h), minute(m)
{
}
...
};
Alternatively:
class Date {
private:
int month;
int day;
int year;
public:
Date(int m = 0, int d = 0, int y = 0) : month(m), day(d), year(y)
{
}
...
};
class Time {
private :
int hour;
int minute;
public:
Time(int h = 0, int m = 0) : hour(h), minute(m)
{
}
...
};
Alternatively (C++11 and later only):
class Date {
private:
int month = 0;
int day = 0;
int year = 0;
public:
Date() = default;
// or:
// Date() : Date(0, 0, 0) {}
Date(int m, int d, int y) : month(m), day(d), year(y)
{
}
...
};
class Time {
private :
int hour = 0;
int minute = 0;
public:
Time() = default;
// or:
// Time() : Time(0, 0) {}
Time(int h, int m) : hour(h), minute(m)
{
}
...
};
construct the array elements explicitly using placement-new so you can use Appointment's non-default constructor on them, eg:
typedef unsigned char AppointmentBuf[sizeof(Appointment)];
// better:
// #include <type_traits>
// using AppointmentBuf = std::aligned_storage<sizeof(Appointment), alignof(Appointment)>::type;
int main(){
AppointmentBuf myAppointments[19];
...
for (int i = 0; i < 19; i++) {
...
new (&myAppointments[i]) Appointment(month, day, year, hour, minute, howLong);
}
...
for (int i = 0; i < 19; i++) {
Appointment &appt = reinterpret_cast<Appointment&>(myAppointments[i]);
// use appt as needed...
}
...
// cleanup
for (int i = 0; i < 19; i++) {
reinterpret_cast<Appointment&>(myAppointments[i]).~Appointment();
}
return 0;
}
Change the array to hold Appointment* pointers, and then construct the array elements dynamically via new using Appointment's non-default constructor, eg:
int main(){
Appointment* myAppointments[19] = {};
...
for (int i = 0; i < 19; i++) {
...
myAppointments[i] = new Appointment(month, day, year, hour, minute, howLong);
}
...
for (int i = 0; i < 19; i++) {
// use myAppointments[i] as needed...
}
...
// cleanup
for (int i = 0; i < 19; i++) {
delete myAppointments[i];
}
return 0;
}
Alternatively (C++11 or later only):
#include <memory>
int main(){
std::unique_ptr<Appointment> myAppointments[19];
...
for (int i = 0; i < 19; i++) {
...
myAppointments[i] = std::make_unique<Appointment>(month, day, year, hour, minute, howLong);
}
...
for (int i = 0; i < 19; i++) {
// use myAppointments[i] as needed...
}
...
// no manual cleanup needed
return 0;
}