Please check my C++

**matsp** · 07-14-2008

Originally Posted by csonx_p

By this you referring to getting the current time from system maybe? Or just set to any hour, minute... I removed the seconds, no relevancy to this program really

I mean you set hour and minute (and second?) to zero if they are not specified.

--
Mats

**csonx_p** · 07-14-2008

Code:

// Overload for reading input streams
istream& operator >> (istream& in, Car& car)
{
	string make, model;
	int ymodel, engCap;
	TankStatus ts;

	in >> make >> model;
	in >> ymodel;
	in >> engCap;
	in >> ts;
	
	car.setCarDetails(make, model, ymodel, engCap, ts);
}

My thoughts are the overloaded function should only have the four lines, not the setCarDetails()...

here's the setCarDetails

Code:

void Car::setCarDetails(string make, string model, unsigned yrModel, 
						unsigned engCap, TankStatus tnkStatus)
{
	make = carMake;
	model = carModel;
	yearModel = yrModel;
	engineCapacity = engCap;
	tankStatus = tnkStatus;
}

OR, can overloaded operators call other functions within?

**matsp** · 07-14-2008

Your code is correct.

If you want to operate directly on car, you either need to make the operator>> function a friend ("friends" are trusted to not do silly things with an object, and thus can see private member variables and functions), or make it a member function of the object itself.

Whether you prefer to call a member setter function or access the member variables directly is pretty much a design decision that can be argued either way, and without any particular knowledge of the overall design/requirements, it would be impossible to say which is better. At this point, you decide what you want to do. The call of the setter has the benefit of being safer - but potentially slower because of the call overhead. I don't think performance (here at least) will be a factor, so I wouldn't worry about that bit.

--
Mats

**csonx_p** · 07-14-2008

Thnx mats & Elysia for your help... There's a progress...

Now i've compiled after the changes which includes the use of the '<<' & '>>' overloaded operators.. I'm gonner post them by step to avoid confusions...

read member function

Code:

void Car::read(istream& indata, Car& car, bool isKeyboard)
{
	indata >> car;
	if(isKeyboard) {
		readDates(indata);
	}
}

it's declaration in class Car

Code:

void read(istream& i, const Car&, bool t);

error..

Code:

error C2511: 'void Car::read(std::istream &,Car &,bool)' : overloaded member function not found in 'Car'

?????

**csonx_p** · 07-14-2008

Code:

// Declare class to hold car details

#include <string>
#include <fstream>
#include <iostream>
#include <iomanip>
#include "RentalDate.h"

using namespace std;

class Car						
{
public: 
	
	Car();						
	
	enum TankStatus {unknown, empty, half, full};	 

	void setCarDetails(string m,string ml,unsigned yrm,unsigned engCap,TankStatus ts);
	static string getTankStatusName(TankStatus);
	bool sameModel(const string&) const;
	bool operator<(const Car&) const;	
	void read(istream&, const Car& c, bool);
	void write(ostream&, bool);
	
	string getModel();
	string getMake();
	unsigned getEngineCap();
	unsigned getYearModel();
	TankStatus getTankStatus();

private:

	string		make;				// Make as in..."toyota"
	string		model;				// Model as in ... "cressida"
	unsigned	engineCapacity;		// Engine capacity may be stored as "1800" not 1.8
	unsigned	yearModel;			
	TankStatus	tankStatus;			// Maybe filled, half-filled, or empty
};

// Overload fstream operators for enum variable
ostream& operator << (ostream& out, Car::TankStatus eStatus);
istream& operator >> (istream& in, Car::TankStatus& eStatus);
istream& operator >> (istream& in, Car& car);
void readDates(Date& dates);

**matsp** · 07-14-2008

Originally Posted by csonx_p

Thnx mats & Elysia for your help... There's a progress...

Now i've compiled after the changes which includes the use of the '<<' & '>>' overloaded operators.. I'm gonner post them by step to avoid confusions...

read member function

Code:

void Car::read(istream& indata, Car& car, bool isKeyboard)
{
	indata >> car;
	if(isKeyboard) {
		readDates(indata);
	}
}

it's declaration in class Car

Code:

void read(istream& i, const Car&, bool t);

error..

Code:

error C2511: 'void Car::read(std::istream &,Car &,bool)' : overloaded member function not found in 'Car'

?????

Hmm. Why would you have a function that reads into a car object, that in itself is declared (and not static) in the Car class. I would either make it a free function (not part of the class), or use the current object (this) as the car object, and not pass it.

I don't know why it's going wrong - perhaps you need std::istream in your class member function?

Edit: And your problem in itself is that in your declaration in the class, you use const Car &, then loose the const in the actual function definition - you should not have const in either place in this instance, as you INTEND to modify car.

--
Mats

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