C++ :: How To Create A Function That Takes A File Object As A Reference Parameter

I have a school project in which need to create a function that takes a File Object as a Reference Parameter. Supposedly, it should allow me to read the first piece of data from others separated by a space from a file. The later be able to continue reading from the next piece of data.

I know how to set things up to read from the data file, such as using

Code:

#include <iostream> , and

Code:

ifstream inputFileName;
inputFile.open ("nameOfFile");

I also understand how to pass a variable by reference to a function. But I simply cannot put the two items together!

I tried using

Code:

void getFileInput (ifstream &); //parameter
getFileInput ("nameOfFile") // call
void getFileInput (ifstream &dataFileName)

In the function I used

Code:

ifstream inputFile;
inputFile.open (dataFileName);

I'm just not getting an understanding of this concept!