File Size is Always Char Array Size...

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

int main() {
  streampos begin, end;
  // streampos type
  /*

  streampos is a specific type used for buffer and file positioning.
  It is the type returned by file.tellg(). Values of this type can
  be safely subtracted from other values of the same type, and can
  also be converted to an integer type large enough to contain the
  size of the file.

  These stream positioning functions can use two particular types:
  streampos and streamoff. These types are also defined as member
  types of the stream class.

  */
  ifstream myfile ("binary_file.bin", ios::binary);
  begin = myfile.tellg(); // get the start position of the stream
  myfile.seekg (0, ios::end);
  // modifies the get postion to be ...
  // 0 offset from the end of the stream
  end = myfile.tellg(); // get the end position of the stream
  if (end-begin == 0) {
    ofstream outFile ("binary_file.bin", ios::binary);
    char words[256] = {};
    cout << "Enter a series of words into"
    << " the file (enter: 'CTR+C' to terminate): \n";
    while (cin.get(words, sizeof(words))) {
      cout << "Writing [" << sizeof(words) << " bytes] to file...\n";
      outFile.write(words, sizeof(words));
    }
    outFile.close();
  } else {
    myfile.close();
    cout << "size is: " << (end-begin) << " bytes.\n";
  }
  return 0;
}