Accessing usb using c++

Lets say that there is a device connected to one of the usb ports in my computer. That device is sending numbers to my computer. I want to create a program that can access the usb port and collect the data from it. I have this code and got stuck here...can someone please help me?

#include <stdio.h>
#include <iostream>
using namespace std;

int main ()
{
FILE * pFile;
pFile = fopen("f:\\[/b]", "r");
system("pause");
fclose(pFile);
return 0;
}