c++ read/write to a file

main.cpp

#include <cstdio>
#include <iostream>
#include <filesystem>
#include <fstream>
 
namespace fs = std::filesystem;

int main()
{
    const std::string filename = std::tmpnam(nullptr);
    {
      std::cout << "File: " << filename << std::endl;
      FILE* fp = std::fopen(filename.c_str(), "w+");
      const std::string data =
      "1\n"
      "11\n"
      "21\n"
      "1211\n"
      "111221\n";
      std::fputs(data.c_str(), fp);
      std::fclose(fp);
    }
    {
        std::cout << "reading..." << std::endl;
        fs::path path = filename;
        std::ifstream file(path, std::ifstream::in);
        //std::ifstream file;
        //file.open(path, std::ifstream::in);
        char c = file.get();
        while (file.good()) {
            std::cout << c;
            c = file.get();
            }
            file.close();
            //std::cout << file << std::endl;
    }
    std::remove(filename.c_str());
}

zz.md

ref: https://coliru.stacked-crooked.com/view?id=3227f6a1752f9fec

g++ -std=c++23  -O2 -Wall -Wextra -pedantic -pthread -pedantic-errors main.cpp -lm  -latomic  && ./a.out
/tmp/ccw6Ksys.o: In function `main':
main.cpp:(.text.startup+0xc): warning: the use of `tmpnam' is dangerous, better use `mkstemp'

possible output

File: /tmp/fileb0L1Ln
reading...
1
11
21
1211
111221