C++ int to string, concatenate strings [duplicate]

Answer 1

Using std::ostringstream:

std::ostringstream os;
os << "File - "  << nStr << ".txt";
std::ofstream resultsFile(os.str().c_str());

Using std::to_string (C++11):

std::string filename = "File - " + std::to_string(nStr) + ".txt";
std::ofstream resultsFile(filename.c_str());