Duplicate Data when I retrieve the data from file in C++ - c++

Question

First of all, there's an data inside my file...
1|Malaysia|UK|One-Way|20|6|20|6|2000|12|12|12|12|12|
The above data is the data inside my file
But when I cout the data, there's an duplicate data...
1|Malaysia|UK|One-Way|20|6|20|6|2000|12|12|12|12|12|
1|Malaysia|UK|One-Way|20|6|20|6|2000|12|12|12|12|12|
So what's the problem when I cout the data???
Here's the code....
void Flight::displayFlight(vector <Flight> &flightProfile)
{
string readFlightID, readPrice, readBusinessList, readBusinessWaitingList, readEconomicList, readEconomicWaitingList;
flightProfile.erase(flightProfile.begin(),flightProfile.end());
ifstream inFlight("Flight.txt");
if(inFlight.fail()) return;
while(!(inFlight.eof()))
{
getline(inFlight,readFlightID,'|');
istringstream(readFlightID)>>flightID;
getline(inFlight,departure,'|');
getline(inFlight,destination,'|');
getline(inFlight,flightType,'|');
getline(inFlight,readBusinessList,'|');
istringstream(readBusinessList)>>businessList;
getline(inFlight,readBusinessWaitingList,'|');
istringstream(readBusinessWaitingList)>>businessWaitingList;
getline(inFlight,readEconomicList,'|');
istringstream(readEconomicList)>>economicList;
getline(inFlight,readEconomicWaitingList,'|');
istringstream(readEconomicWaitingList)>>economicWaitingList;
getline(inFlight,readPrice,'|');
istringstream(readPrice)>>price;
getline(inFlight, day,'|');
getline(inFlight, month,'|');
getline(inFlight, year,'|');
getline(inFlight, hour,'|');
getline(inFlight, min,'|');
inFlight.ignore(numeric_limits<streamsize>::max(), '\n');
cout<<flightID<<departure<<destination<<flightType<<businessList<<businessWaitingList<<economicList<<economicWaitingList<<price<<day<<month<<year<<hour<<min<<endl;
}
inFlight.close();
}

Answer 1

Your (and others) common mistake is that the eof-bit is only set on input operations (RTFM).
The correct way to read a file line by line would be to do:
if (myfile.is_open())
{
while ( getline (myfile,line) )
{
cout << line << endl;
}
myfile.close();
}

Answer 2

You always need to check after you read from a stream if the stream is in a good state! If reading of the data failed, e.g., because the end of the stream was reached, the stream will be in a fail state. For example
while (std::getline(inFlight, readFlightID)
&& std::istringstream(readFlightId) >> flightID
&& std::getline(inFlight, departure)
...
) {
// now process the read data
}
BTW, note that the trick using a temporary stream only works like this if the target type is a member of std::istream. If it is not, you'll need to extra a reference from the stream, e.g. using
std::istringstream("some text") >> std::skipws >> value

Answer 3

That's because you're not checking that your getline succeeds.
The last time through the loop, it probably fails (because
you've read all of the data), so you pick up the old values.
This is not the way to read line based input. For starters,
line based input should be read line by line:
std::string line;
while ( std::getline( inFlight, line ) ) {
// Parse line here...
}
There are many ways to parse the line. One of the most common
solutions is to put it into an std::istringstream and read
from that. That's probably overkill for what you're doing,
however; you need probably something like boost::split (which
you can knock up in less than an hour if you can't use Boost).
At any rate, while ( !someIStream.eof() ) is never correct.
Two other quick comments: you shouldn't define your variables
before you need them, and there's no real point in closing
inFlight if it's immediately going out of scope.