Question

I created this program:

#include <iostream>
#include <fstream>
using namespace std;

int main () {
  fstream file;
  file.open("test.bin", ios::in | ios::out | ios::binary);
  if(!file.is_open())
  {
      return -1;
  }
  int n = 5;
  int x;
  file.write(reinterpret_cast<char*>(&n), sizeof(n));
  file.read(reinterpret_cast<char*>(&x), sizeof(x));
  std::cout<<x;
  file.close();
  std::cin.ignore();
  return 0;
}

that’s supposed to write an integer “n” into a .bin file “test.bin”, then read data from “test.bin” into an integer “x”, then displays “x” to the screen.

When I run the program, it displays not 5, but -842150451. Why does this occur, and how can I fix it?

Answer 1

Isn’t the file.write() moving the current file pointer when you write it, causing you to read data from the first location AFTER the written data?