Open a file as binary file and get its size : file open mode « File Stream « C++ Tutorial

1. C++ Tutorial
2. File Stream
3. file open mode

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

int main () 
{
  long start,end;
  ifstream myfile ("test.txt", ios::in|ios::binary);
  
  start = myfile.tellg();
  myfile.seekg (0, ios::end);
  end = myfile.tellg();
  myfile.close();
  
  cout << "size of " << "test.txt";
  cout << " is " << (end-start) << " bytes.\n";
  return 0;
}

size of test.txt is 25 bytes.