C++ newbie question: output to file and later add to that file?

[Antst]

Hi everyone:

I have written c++ code for performing a calculation. I know how to output my results to a file (example below).

What I want to do now is include a loop in my calculation, so that each loop represents a new time step. My problem is, I don't want to make a new output/results file for each new time step. I want one results file, where results are concatenated/added into the file for each new time step.

Is this possible? If so, I would very much appreciate an example! Thanks a lot.

ofstream xOut;
xOut.open ("x.txt");

for(int i = 0; i < d_xi; i++)
{
for(int j = 0; j < d_xi; j++)
{
xOut << gridPtMatX(i,j) << " ";
}
xOut << endl;
}
xOut.close();

 

[oops]

You need to open your file in append mode:

xOut.open ("x.txt", ios:ut || ios::app);