Range Iterator C++

range.cc

#include <iostream>
#include <stdexcept>

struct RangeIterator {
  int64_t i, s = 1;
  const RangeIterator &operator++() {
    i += s;
    return *this;
  }
  const bool operator!=(const RangeIterator &it) {
    return it.i != this->i;
  }
  const int64_t operator*() {
    return i;
  }
  RangeIterator(int64_t _i) : i(_i) {}
  RangeIterator(int64_t _i, int64_t _s) : i(_i), s(_s) {}
};

class range {
  private:
    int64_t s, e, step = 1;
  public:
    typedef RangeIterator iterator;
    const iterator begin() {
      return iterator(s, step);
    }
    const iterator end() {
      return iterator(e, step);
    }
    range(int64_t _e) : s(0), e(_e) {}
    range(int64_t _s, int64_t _e) : s(_s > _e ? _e : _s), e(_e) {}
    range(int64_t _s, int64_t _e, int64_t _step) {
      if (_step == 0) {
        throw std::invalid_argument("step argument must not be zero");
      }
      if (_step < 0 && _s < _e) {
        _s = _e;
      } else if (_step > 0 && _s > _e) {
        _e = _s;
      }
      if (_step > 0 && _e - _s < _step) {
        _step = _e - _s;
      } else if (_step < 0 && _e - _s > _step) {
        _step = _e - _s;
      }
      s = _s;
      e = _e;
      step = _step;
    }
};