handling-failure-with-file-stream.cpp

#include <fstream>
#include <iostream>
#include <string>

using namespace std;

ifstream open(const char* path, ios_base::openmode mode = ios_base::in) {
  ifstream file{path, mode};
  if (!file.is_open()) {
    string err{"Unable to open file"};
    err.append(path);
    throw runtime_error{err};
  }
  file.exceptions(ifstream::badbit);
  return file;
}

int main() {
  auto file = open("numbers.txt");
  auto maximum = numeric_limits<int>::min();
  int value;
  while (file >> value) maximum = maximum < value ? value : maximum;
  cout << "Maximum found was " << maximum << endl;
}