C++ :: Taking Input File And Doing Calculation

I am trying to work on a C++ program to calculate the quadratic formula using input files and classes. I have written my class, but I am trying to find a way to take an input file with unknown number of lines of coefficients. How do I take each integer from each line and set that value as "a" and "b" and so forth, then start over on the next line?

This is what i have so far.

fstream inputfile;//users input quadratic coefficients file
ofstream outputfile;// outputs a file with solutions
int main(int argc, char *argv[])// argc is argument count, char *argv[] is array of array of characters for arguments {
string dataline;
getline(inputfile, dataline);

[code].....