C++ problem with string stream istringstream

I am reading a file in the following format

1001    16000     300    12.50
2002    24000     360    10.50
3003    30000     300     9.50

where the items are: loan id, principal, months, interest rate.

I'm not sure what it is that I am doing wrong with my input string stream, but I am not reading the values correctly because only the loan id is read correctly. Everything else is zero. Sorry this is a homework, but I just wanted to know开发者_StackOverflow if you could help me identify my error.

if( inputstream.is_open() ){

        /** print the results **/
        cout << fixed << showpoint << setprecision(2);
        cout << "ID " << "\tPrincipal" << "\tDuration" << "\tInterest" << "\tPayment" <<"\tTotal Payment" << endl;
        cout << "---------------------------------------------------------------------------------------------" << endl;

        /** assign line read while we haven't reached end of file **/
        string line;
        istringstream instream;
        while( inputstream >> line ){
            instream.clear();
            instream.str(line);

            /** assing values **/
            instream >> loanid >> principal >> duration >> interest;


            /** compute monthly payment **/
            double ratem = interest / 1200.0;
            double expm = (1.0 + ratem);
            payment = (ratem * pow(expm, duration) * principal) / (pow(expm, duration) - 1.0);

            /** computer total payment **/
            totalPayment = payment * duration;

            /** print out calculations **/
            cout << loanid << "\t$" << principal <<"\t" << duration << "mo" << "\t" << interest << "\t$" << payment << "\t$" << totalPayment << endl;

        }
    }

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You are not reading linewise. Replace the condition by

while( getline(inputstream, line) )

If you use operator>> it will extract only the first word to line.