#include <iostream>
#include <vector>
#include <cassert>

static char char2digit(char c) {
  if (c >= '0' && c <= '9')
    return (c - '0');
  if (c >= 'A' && c <= 'F')
    return (c - 'A' + 10);
  if (c >= 'a' && c <= 'f')
    return (c - 'a' + 10);
  assert(0);
  return 0;
}

std::vector<char> set(const std::string &hexstring) {
  std::vector<char> bytes;
  size_t idx = 0;
  bool neg = false;

  if (hexstring[idx] == '-') {
    neg = true;
    ++idx;
  }
  if (hexstring[idx] == '0' && hexstring[idx + 1] == 'x') {
    idx += 2;
  }
  size_t size = hexstring.size();
  assert((size - idx) > 0);

  if ((size - idx) % 2 != 0) {
    char c = char2digit(hexstring[idx++]);
    bytes.push_back(c);
  }

  for (; idx < size; ) {
    char c = char2digit(hexstring[idx++]) << 4;
    c += char2digit(hexstring[idx++]);
    bytes.push_back(c);
  }
  return bytes;
}

int main() {
  auto v = set("0xaba");
  for (const auto b : v) {
    std::cout << static_cast<int>(static_cast<unsigned char>(b)) << "\n";
  }
}