how to call this method

[technologist]

Hi,

I've split the code into 2 pieces. However I've failed to call the SetDate function. How do I call a method that's a part of a class but put outside of it? In the .cpp how do I call SetDate fx? I've tried a few different ways.

Date.h

#ifndef DATE_H
#define DATE_H

class Date
{
private:
    int m_year;
    int m_month;
    int m_day;
public:
    Date(int year, int month, int day);

    void SetDate(int year, int month, int day);

    int getYear() { return m_year; }
    int getMonth() { return m_month; }
    int getDay()  { return m_day; }
};

#endif

Date.cpp

#include "Date.h"
#include<iostream>
// Date constructor
Date::Date(int year, int month, int day)
{
    SetDate(year, month, day);
}

// Date member function
void Date::SetDate(int year, int month, int day)
{
    m_month = month;
    m_day = day;
    m_year = year;
    std::cout<<"here";
}
int main()
{

	//Date date;
	return 0;
}

//no errors with Date date commented out

[Peter87]

You forgot to pass arguments to the constructor.

int main()
{
	Date date(2016, 8, 1);
	return 0;
}

[AbstractionAnon]

Line 20: You're trying to call Date's default constructor. However, you don't have a default constructor.

[E0p9LyTq]

date.h:

#ifndef DATE_H
#define DATE_H

using USHORT = unsigned short;

class Date
{
public:
   Date();
   Date(USHORT year, USHORT month, USHORT day);

   void SetDate(USHORT year, USHORT month, USHORT day);

   USHORT getYear() { return m_year; }
   USHORT getMonth() { return m_month; }
   USHORT getDay()  { return m_day; }

private:
   USHORT m_year;
   USHORT m_month;
   USHORT m_day;
};

#endif 

date.cpp:

#include<iostream>
#include "date.h"

// default Date constructor
Date::Date()
{
   SetDate(1970, 1, 1);
}

// Date constructor
Date::Date(USHORT year, USHORT month, USHORT day)
{
   SetDate(year, month, day);
}

// Date member function
void Date::SetDate(USHORT year, USHORT month, USHORT day)
{
   m_month = month;
   m_day = day;
   m_year = year;
   // std::cout<<"here";
}

main.cpp:

#include <iostream>
#include "date.h"

int main ()
{
   Date date1;

   std::cout << "The first date is "
      << date1.getDay() << "/" << date1.getMonth() << "/" << date1.getYear() << ".\n";

   Date date2(2016, 8, 1);

   std::cout << "The second date is "
      << date2.getDay() << "/" << date2.getMonth() << "/" << date2.getYear() << ".\n";
}

The first date is 1/1/1970.
The second date is 1/8/2016.

[E0p9LyTq]

If you wanted to get fancy and output your class as if it were a Plain Old Data (POD) type, you can overload std::ostream's insertion operator (<<):

date.h:

#ifndef DATE_H
#define DATE_H

using USHORT = unsigned short;

class Date
{
public:
   Date();
   Date(USHORT year, USHORT month, USHORT day);

   void SetDate(USHORT year, USHORT month, USHORT day);

   friend std::ostream& operator<<(std::ostream& os, const Date obj);

   USHORT getYear() { return m_year; }
   USHORT getMonth() { return m_month; }
   USHORT getDay()  { return m_day; }

private:
   USHORT m_year;
   USHORT m_month;
   USHORT m_day;
};

#endif 

date.cpp:

#include<iostream>
#include "date.h"

// default Date constructor
Date::Date()
{
   SetDate(1970, 1, 1);
}

// Date constructor
Date::Date(USHORT year, USHORT month, USHORT day)
{
   SetDate(year, month, day);
}

std::ostream& operator<< (std::ostream& os, const Date obj) 
{
   return os << obj.m_day << "/" << obj.m_month << "/" << obj.m_year;
}

// Date member function
void Date::SetDate(USHORT year, USHORT month, USHORT day)
{
   m_month = month;
   m_day = day;
   m_year = year;
   // std::cout<<"here";
}

main.cpp:

#include <iostream>
#include "date.h"

int main ()
{
   Date date1;

   std::cout << "The first date is "
      << date1.getDay() << "/" << date1.getMonth() << "/" << date1.getYear() << ".\n";

   Date date2(2016, 8, 1);

   std::cout << "The second date is "
      << date2.getDay() << "/" << date2.getMonth() << "/" << date2.getYear() << ".\n";

   std::cout << "\nAgain, the second date is " << date2 << ".\n";
}

The first date is 1/1/1970.
The second date is 1/8/2016.

Again, the second date is 1/8/2016.

[TheIdeasMan]

Hi,

I think you should also become familiar with the constructor having a member initialization list:

// Date constructor
Date::Date(const USHORT yearArg, const USHORT monthArg, const USHORT dayArg)
: // colon introduces initialiser list
year(yearArg),  // direct initialisation not assignment
month(monthArg), //same order as class delcaration
day(dayArg)          //make sure to initialise all of them
{
   //SetDate(year, month, day);
// do validation here, throw if there is a problem
// invariants - call private functions to keep this tidy
// valid range for  year
// valid range for  month
// valid range for  day
// Leap Year validation for month and day

// object is not deemed to have been created until the end of the constructor is reached
}

You can still have the SetDate function for when the date is changed after the object is created.

Having the SetDate function and calling it from the ctr seems like a good idea, but it is a little inefficient. Before the opening brace of the ctr, the compiler assigns default values for each member variable; if one then gives them values by assignment - that is where the inefficiency lies - it is happening twice and there are unnamed temporaries being created. The member initializer list avoids this.

http://en.cppreference.com/w/cpp/language/initializer_list

@FurryGuy

Not sure whether you were aware of this header file:
http://en.cppreference.com/w/cpp/header/cstdint

[E0p9LyTq]

@TheIdeasMan,

I am aware of that C library header, I preferred in this instance to use an explicit POD type (unsigned short).

[technologist]

@TheIdeasMan, et al

Recently have been introduced to c++11 uniform initialization list for constructors. The problem at hand here was the constructor wasn't called. Thanks for the perspective on the greater issues and to everyone who contributed.