c++ iostream - output file is not created - c++

Question

I added some commands to produce an output file in methods of a given class. This worked perfectly well, and output file was produced during execution. Now that I made major changes to the code (but not at all to the output file commands), I am not producing output correctly anymore? Where can this come from? The code I changed seems not have any connexion to output commands. Constructor looks like
solverMethod::solverMethod(solverInput*inp_):solverMethod(inp_)
{
ndim = m_input->getNbParams();
bestFuncEval = DBL_MAX;
NMAX = m_input->getMaxIter();
FTOL = m_input->getTolerance();
NITER = 0;
logMode = true;
osOutput.open("F://Output.txt") ;
}
where member boolean logMode decide whether comments are active or not.
In different methods, I have code like
if(logMode)
{
osOutput << "\n";
osOutput << " - - BUILD ";
osOutput << "\n";
osOutput << "INITIAL";
osOutput << "\n";
for(int k=0;k<npts;k++)
{
for(int j=0;j<m_ndim;j++)
{
osOutput << s_[k][j] ;
osOutput << ", ";
}
}
osOutput << "\n";
}
to produce comments
and then I have at the end of major method:
// ....
osOutput.close();
return true;
}
Do you have any further info

Answer 1

What is the status of the stream after the open? You almost always
want to check whether the open succeeded (and whether all of the
writes succeeded after the close). You might try something like:
osOutput.open(...);
if ( !osOutput.is_open() ) {
std::cerr << "Cannot create ..., error was: " << strerror( errno);
}
This will give you more information about what is wrong.