Thread: Push_back not storing data to vector

For some reason my vector doesn't push_back data (or accept data)

Code:

class Fleet
{
private:

	typedef vector<Car> CarFleet;
	typedef CarFleet::iterator FleetIterator;

public:

	Fleet();
        void ReadFleetFromFile();

private:
	CarFleet fleet; 
};

Code:

void Fleet::ReadFleetFromFile()
{					
	char filename[MAX_PATH] ;

	puts("\n\nPlease enter the text file to open:\n");
	cin >> filename;

	ifstream fleetin;
	fleetin.open (filename);

	/* Ensure file was opened, otherwise send an error */
	if ( fleetin.fail() )
	{
		puts("");
		perror("ERROR! while trying to open file");
		exit(1);
	}
	else
	{
		// Read number of records from file
		while (!fleetin.eof())
		{
			Car car;	

			if( car.Read(fleetin) )
				fleet.push_back(car); // After this line car contains data, but fleet doesn't
		}
		puts("\nProcessed reading...");		
	}

	fleetin.close();

}

I used a debug (F5) and a break point at fleet.push_back(car) ... Car does contain data read from file, after executing this line, by using VS2005 watch window on fleet, i just see {_Myfirst='some address' _Mylast='address' Myend='address again'} ... An when i expoand the plus sign on fleet watch window to check elements, there are 'error' with 0 values... Completely lost here

Originally Posted by Darryl

I'd like to see the car.Read() function, my guess is that it is returning false and so fleet.push_back is never getting called.

Even if you you don't have a custom copy constructor(but needed one), the default constructor will push something back, so it shouldn't be empty.

Code:

// Read fleet data from either keyboard or file
bool Car::Read(istream& indata)
{
	if ( !(indata >> *this) )
		return false;
	return true;
}

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

	in >> make >> model;
	in >> regNo;
	in >> ymodel;
	in >> engCap;
	in >> ts;
	
	// Ensure correct tank details
	if ( (ts>3) || (ts<0) ) {
		ts=Car::unknown;
	}

	car.setCarDetails(make, model, regNo, ymodel, engCap, ts);

	return in;
}

Don't use the debugger to determine the vector's size. Call fleet.size() and look at the output of that function.

>> while (!fleetin.eof())
This won't help, or will cause problems. Use:

Code:

Car car;	
while (fleetin >> car)
	fleet.push_back(car);

You should probably also fix your operator>> so that it checks the state of in before it calls setCarDetails, although I'm not sure it matters in this case.

If you're still having trouble, put a breakpoint in your operator>> and watch it read the data in, does that work?

Originally Posted by csonx_p

I moved this code from Fleet to Car

Code:

// Read fleet data from either keyboard or file
int Car::Read(istream& indata)
{ 
	// Read each record
	while ( indata >> *this ) {	
		fleet.push_back(*this);
	}
	return (int) fleet.size();
}

Code:

//Back to fleet : where read is called ... (in Fleet.cpp)

Car car;	
		
if ( car.Read(fleetin) )
{
	puts("\nProcessed reading...");
	SortAlpha();		
}
else
puts("\nData was unsuccessfully read !!...");

But now Car cannot see Fleet "flee.push_back" ... If i try to include fleet.h inside Car.h, there's a problem because fleet includes car already.. ": error C2011: 'Car' : 'class' type redefinition"

k, i did a forward declaration in Fleet.h (class Car) since i'm only declaring Car as a vector in Fleet. I then included Fleet.h in car.h. After doing this in car

Code:

Fleet::fleet.push_back(*this);

i get : error C2228: left of '.push_back' must have class/struct/union ???

Your original approach was right. The Cars should be created in a read function of fleet.
The problem you have now is that a car doesn't have a member fleet. That's why you cannot call

Code:

fleet.push_back(*this);

from inside Car::Read().
You could pass a pointer or reference to the fleet the car belongs to, in the constructor of car.
Kurt

>> I moved this code from Fleet to Car
Why? I liked it better the other way. A Car should not know about a Fleet.

Originally Posted by laserlight

Suppose that iter points to the last element. Now, iter+1 <= fleet.end(), since iter+1 == fleet.end(). But you compare iter->getMake() with (iter+1)->getMake() and iter->getModel() with (iter+1)->getModel(), thus dereferencing the one past the end iterator twice. A possible solution is to change it to:

Code:

	for
	(	;
		(iter+1) != fleet.end() &&
		iter->getMake() == (iter+1)->getMake() &&
		iter->getModel() == (iter+1)->getModel()
		;
		++iter;
	)

cool, solved the error