lib/outfile.cpp

The following code example is taken from the book
C++ Move Semantics - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2020
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#include <iostream>
#include <fstream>
#include <stream>

std::ofstream openToWrite(const std::string& name)
{
  std::ofstream file(name);           // open a file to write to
  if (!file) {
    std::cerr << "can't open file '" << name << "'\n";
    std::exit(EXIT_FAILURE);
  }
  return file;                        // return ownership (open file)
}

void storeData(std::ofstream fstrm)   // takes ownership of file (but this might change)
{
  fstrm << 42 << '\n';
}                                     // closes the file

int main()
{
  auto outFile{openToWrite("iostream.tmp")};  // open file
  storeData(std::move(outFile));              // store data

  // better ensure that the file is closed:
  if (outFile.is_open()) {
    outFile.close();
  }
}