C++: Possibilities For Using the 'this' Pointer With "get" Functions to Replace Cout Statements

Question

After just learning how to cascade multiple mutator function calls by defining those functions with return type "reference to an object of a class C" (i.e., C &setHeight( int ) ) in conjunction with corresponding 'return *this' statements, I would very much like to know if a similar method allows an object's data members to be returned from a single "get" function.
I have a simple "invoice" class, with an object from another class, "Date". This data member object itself contains private data that store the standard date for the "date of purchase" of a hypothetical product (for which the object was created). Although in "Date", three int members store the date components, I would like to somehow cascade calls to the three corresponding get functions, belonging to the Date object, in my "date of purchase" accessor, as some single accessor/get appears to be required, and because this style seems preferable to completing the task with a cout statement. In other words, if some get function must be used to display the full date, I'd rather it were displayed formatted, with a single call within a print statement in the client (function main), than by a function that merely prints a formatted statement when called from main.

//Invoice.h

#ifndef DATE_H
#define DATE_H

#include "Date.h"
...using namespace std. (Assume all other necessary libraries, classes, are included)

class Invoice {

public:

Invoice(); // Default constructor
Invoice( Date &, string );
setDateOfPurchase( int, int, int );
getDateOfPurchase();

private:

Date DateOfPurchase;
string description;

}; // end class definition

#endif

---

Member function definition below...

//Invoice.cpp
#include "Date.h"
(Again, please assume the necessary inclusions are made here)


Invoice::Invoice(){ 

DateOfPurchase.month = 1;
DateOfPurchase.day = 1;
DateOfPurchase.year = 1999;
} // end Default constructor definition

Invoice::Invoice( Date &purchaseDate, string desc ):
DateOfPurchase( purchaseDate ),
description( desc )
{} // No body

Invoice &Invoice::setDateOP( int m, int d, int y ) {
// The Date class definition is not explicitly defined; please assume these simply accept
// one int argument each.
DateOfPurchase.setMonth( m );
DateOfPurchase.setDay( d );
DateOfPurchase.setYear( y );

return *this;
} // End mutator definition

The header for my accessor function intended to retrieve the full date stored in object DateOfPurchase looks like the following:

Invoice &Invoice::getDateOrd(){

//gets month, day, and year, possibly through utilizing dereferenced 'this' pointer (*this)

} // end getDateOrd definition

---

function main below...

In main: // Creation of a Date object, which will be passed by reference to the invoice constructor. Date today( 11, 10, 2014 );

Invoice firstSale( today, A corkscrew: product# 88090 );

// Cascading call to each member function of *member data object* DateOfPurchase
firstSale.setMonth( 11 ).setDay( 12 ).setYear( 2014 );   

---

Hopefully, this demonstrates a basic application of the cascading call with "set" functions. Now for "get" functions... (By the way, I'm using Deitel & Deitel, 2013, 7th edition)

Answer 1

Use << operator overloading in the Invoice class

add the below code into your Invoice class.

friend ostream &operator<<( ostream &output,
                                 const Invoice  &invoice )
{
    output << "F : " << invoice.DateOfPurchase.dd << " " << invoice.DateOfPurchase.mm<<" "<<invoice.DateOfPurchase.yy;
   return output;
}

You can directly call as

Invoice invoice;
cout<<invoice;

Hope it will solve your problem.