Merging Two Files using C++

[ckoniecny]

Is there a simple way of merging File1 and File2 into OutFile without the use of arrays, only using fstream?

File1:
111 Joe Smith
333 Steve Smith
555 Ron Smith

File2:
222 Don Smith
444 Randy Smith

OutFile:
111 Joe Smith
222 Randy Smith
333 Steve Smith
444 Randy Smith
555 Ron Smith

[Chazwazza]

Why don't you want to use arrays? (I can't think of any other way)

[ckoniecny]

Unfortunately to make my life more difficult I was told not to. This is the code I have so far:

#include <iostream>
#include <fstream>

using namespace std;

int main()
{
        ifstream File1;
        ifstream File2;
        ofstream outFile;

        string File1_fName, File1_lName;
        string File2_fName, File2_lName;
        int File1_acctNum, File2_acctNum;

        File1.open("file1", ios::in);
        File2.open("file2", ios::in);
        outFile.open("out.txt", ios::out);

        File1 >> File1_acctNum >> File1_fName >> File1_lName;
        File2 >> File2_acctNum >> File2_fName >> File2_lName;
        while (!File1.eof() && !File2.eof())
        {
                if (File2_acctNum > File1_acctNum)
                {
                        outFile << File1_acctNum << '\t' << File1_fName << '\t'
                                << File1_lName << " *\n";
                        outFile << File2_acctNum << '\t' << File2_fName << '\t'
                                << File2_lName << " *\n";
                        File1 >> File1_acctNum >> File1_fName >> File1_lName;
                        File2 >> File2_acctNum >> File2_fName >> File2_lName;
                        cout << File2_acctNum << "\t" << File2_fName << "\t" << File2_lName << endl;
                }
                else if (File1.eof())
                {
                        while (!File2.eof())
                        {
                                outFile << File2_acctNum << '\t' << File2_fName << '\t'
                                        << File2_lName << '\n';
                        }
                }
                else if (File2.eof())
                {
                        while(!File1.eof())
                        {
                                outFile << File1_acctNum << '\t' << File1_fName << '\t'
                                        << File1_lName << '\n';
                        }
                }

        }
        return 0;
}

[sunburnt]

Absolutely it's possible. The algorithm is pretty simple. here's a psuedcode example.

// read a line from reach file (file a, file b)
storedA = a.readline();
storedB = b.readline();
   
// loop until one of the files is empty
while(!a.eof() && !b.eof())
{
   // if a comes before b, write it, and read the next line from A.
   // loop until this next line doesn't come before line B
   while(storedA comes before storedB)
   {
      write(storedA);
      storedA = a.readline();
   }
   
   // repeat the process for B < A.
   while(storedB comes before storedA)
   {
      write(storedB);
      storedB = b.readline();
   }
   
}

// here check if either of the files has reached End Of File.
// if true, write the rest of the other file.

You probably need to check for EOF inside each of the inner while loops, but I left that out. Good luck!

[CornedBee]

Don't use eof() in loop conditions. Directly check the stream objects.