std::basic_fstream

#include <iostream>
#include <fstream>
#include <string>
 
int main() {
  std::string filename = "test.bin";
  std::fstream s(filename, s.binary | s.trunc | s.in | s.out);
  if (!s.is_open()) {
    std::cout << "failed to open " << filename << '\n';
  } else {
    // write
    double d = 3.14;
    s.write(reinterpret_cast<char*>(&d), sizeof d); // binary output
    s << 123 << "abc";                              // text output
 
    // for fstream, this moves the file position pointer (both put and get)
    s.seekp(0);
 
    // read
    s.read(reinterpret_cast<char*>(&d), sizeof d); // binary input
    int n;
    std::string str;
    if (s >> n >> str)                             // text input
      std::cout << "read back from file: " << d << ' ' << n << ' ' << str << '\n';
  }
}