//Reads three numbers from the file infile.dat, sums the numbers,
//and writes the sum to the file outfile.dat. 
#include <fstream.h>
#include <iostream.h>
#include <stdlib.h>

int main()
{
    ifstream in_stream;
    ofstream out_stream;

    in_stream.open("infile.dat");
    if (in_stream.fail())
    {
        cout << "Input file opening failed.\n";
        exit(1);
    }

    out_stream.open("outfile.dat");
    if (out_stream.fail())
    {
        cout << "Output file opening failed.\n";
        exit(1);
    }

    int first, second, third;
    in_stream >> first >> second >> third;
    out_stream << "The sum of the first 3\n"
               << "numbers in infile.dat\n"
               << "is " << (first + second + third)
               << endl;

    in_stream.close();
    out_stream.close();

    return 0;
}