C++ Data File with extra empty line

Question

I have data files with extra empty lines in them at the end. This is causing problems with reading in the data lines. I'm using:

while (datFile.good())

but .eof() didn't work either.

Any suggestions?

    while (datFile.good())
    {
        getline (datFile, line);

        istringstream liness(line);

        int z = 0;

        while (z <= index)
        {
            while (liness >> temp)
            {
                if (z == 0)
                {
                    values[0].push_back(atof(temp.c_str()));
                }

                if (z == index)
                {
                    values[1].push_back(atof(temp.c_str()));
                }

                cout << temp << endl;

                z++;
            }
        }

    }

My program just sits there. How would I "read the empty lines"? The data is columnar in nature. Should I post more code? — pbhuter, Feb 03 '12 at 17:41
Why don't you compare the string length after read and exit, once you start getting the zero length record. — Roopesh Majeti, Feb 03 '12 at 17:42
Your code should even fail when there are no empty lines at the end, because of the good old [`while(!eof)` error](http://stackoverflow.com/q/5605125/743214). — Christian Rau, Feb 03 '12 at 17:56

score 2 · Answer 1 · edited Feb 03 '12 at 17:56

2

Thou shalt use the stream's status after thy read!

You didn't post enough code to tell but input always looks something like this:

while (in >> data) {
    process(data);
}

Whether you use formatted input or unformatted input diesn't matter either. Also, good() is generally not that useful aabd eof() is only useful to suppress an error message: if you read failed it may be OK that it failed because you read all the data. It is never a useful condition to determine whether a read was successful: eof() can yield true although the read was successful.

edited Feb 03 '12 at 17:56

Robᵩ

163,533
20
239
308

answered Feb 03 '12 at 17:43

Dietmar Kühl

150,225
13
225
380

`while (datFile >> ??) { process(datFile); }` – pbhuter Feb 03 '12 at 17:56
@user1187621 In your case it's actually `while(getline(datFile, line))`. – Christian Rau Feb 03 '12 at 17:58

score 2 · Answer 2 · answered Feb 03 '12 at 17:58

2

while (getline (datFile, line))
{

    istringstream liness(line);

    // the rest of the loop is unchanged.
    ...
}

answered Feb 03 '12 at 17:58

Robᵩ

163,533
20
239
308

C++ Data File with extra empty line

2 Answers2