Create filename with current time stamp (c++) without c++20
Code log.cpp #include <fstream> #include <iostream> #include <iomanip> #include <ctime> #include <sstream> int main() { auto t = std::time(nullptr); auto tm = *std::localtime(&t); std::stringstream transTime; transTime << std::put_time(&tm, "%Y%m%d-%H%M%S"); std::string fileName = "example-" + transTime.str() ; fileName.append(".txt"); std::cout << fileName << std::endl; std::ofstream file(fileName, std::ios::app); file << "Writing this to a file.\n"; file.close() } Build and run > clang log.cpp -o log.exe Or > "c:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat" x64 > cl log.cpp /Fe /EHsc