#include <iostream>
#include <fstream>
#include <cstdlib>
#include <string>
using namespace std;

void readFile(const string& filename);

int main()
{
    readFile("colors1.txt");
    readFile("colors2.txt");
    return 0;
}

void readFile(const string& filename)
{
    ifstream fin(filename.c_str());
    string buffer;
    if (!fin)
    {
        cerr << "Can't open " << filename << endl;
        exit(1);
    }
    while (!fin.eof())
    {
        fin >> buffer;
        cout << buffer << endl;
    }
    cout << "End of file" << endl;
    fin.close();
}

*****  OUTPUT  *****

red
white
blue
blue
End of file
red
white
blue
End of file

Input Files

colors1.txt

red white blue

colors2.txt

red white blue

Questions

Are all the header files required?  Why?
Is the fin.close() necessary at the end of the readFile() function?
Why is the filename passed as const string&?
How can you change the code to process either file correctly?