Well, here is the gist of the problem. When I read in a file of integers, if there is a formatting character at the end, the last integer is repeated. For instance, in the code, it is reading i01.dat. If that file reads as follows:
2
3
4
5

with the newline character (or tab character, or whatever) at the end, then the five is printed twice when I cout the input even though I tried to use a break for the .eof() or .fail(). I have tried to use an if statement to test for \\n or \\t (i.e. if (i != \\n)) but the compiler does not understand this so I am obviously not testing properly. Please help me understand this. Here's what I've got so far.

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

struct CommandLineException
{
CommandLineException(int max, int actual)
  {
    cout << endl << "Too many command line arguments." << endl;
    cout << "A maximum of " << max << " arguments are permitted." << endl;
    cout << actual << " arguments were entered." << endl;
  }
};

struct FileException
{
  FileException(char* fn)
  {
    cout << endl << "File " << fn << " could not be opened." << endl;
  }
};

int main(int argc, char* argv[])
{

  try
  {
    char ifn[255], ofn[255];
    switch(argc)
    {
      case 1:
        cout << "Enter the input file name. ";
        cin >> ifn;
        cout << "Enter the output file name. ";
        cin >> ofn;
        break;
      case 2:
        strcpy(ifn, argv[1]);
        cout << "Enter the output file name. ";
        cin >> ofn;
        break;
      case 3:
        strcpy(ifn, argv[1]);
        strcpy(ofn, argv[2]);
        break;
      default:
        throw CommandLineException(2, argc - 1);
        break;
    }
    ifstream i(ifn); if(!i) throw FileException(ifn);
    ofstream o(ofn); if(!o) throw FileException(ofn);

    int testmsg;
    while (true)
    {
    if (i.eof()) break;
    i >> testmsg;
    cout << testmsg << " ";
    }

    o.close();
    i.close();
  }
  catch(...)
  {
    cout << "Program terminated." << endl;
    exit(EXIT_FAILURE);
  }

  return 0;
}
int testmsg;
    while (true)
    {
    if (i.eof()) break;
    i >> testmsg;
    cout << testmsg << " ";
    }

Try

while(!eof)

or

do
{
i >> testmsg;
cout << testmsg << endl;
}while(testmsg);

Try

while(!eof)

I tried this one

while (!i.eof)
{blah blah}

and it tells me "invalid use of memeber (did you forget the '&' ?)'
"in argument to unary !"

I also tried this with

while (!eof)

and it tells me that this is " 'eof' undeclared (first use this function)"

or

do
{
i >> testmsg;
cout << testmsg << endl;
}while(testmsg);

I tried this one also and it works but with the same problem I originally described. Thanks for the response though.

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