C++ :: CSV Parser - Infile Using Variable Filename?

So. I have a CSV Parser that I built. It works very well. The way it currently works is that I have the parser in a header file "CSV_Parser". So my .cpp code would look like this:

#include <iostream>
#include <eigen3/Eigen/Dense>
#include "CSV_Parser.h"
using namespace std;
using Eigen;

[Code] ....

This all works great. I am running Eclipse in Linux (Xubuntu to be precise). In the header file the .csv is opened as follows:

ifstream infile;
infile.open("/home/karrotman/Desktop/Matrix.csv");

What I would like is for the user to be able to change the file that the parser is opening through the main .cpp file. In other words, is there a way to create some variable, say "FileName" and do the following:

CSV firstMat;
string MatrixA = "/home/karrotman/Desktop/Matrix1.csv";
firstMat.extract(MatrixA);
CSV secondMat;
string MatrixB = "/home/karrotman/Desktop/Matrix2.csv";
secondMat.extract(MatrixB);

And then the .h would now say:

void extract(string FileName)
...
ifstream infile;
infile.open(FileName);

Obviously this does not work. Ultimately the goal is for me to open 4 .csvs at one time so I can do numerical operations on them.