Negative values from get_value_by_key about libosmium

[joto]

get_value_by_key returns nullptr if the key doesn't exists. You have to check against that before using the value.

[milliams]

Even if I do

void node(const osmium::Node& node)
{
  const char* postcodeValue = node.tags().get_value_by_key("addr:postcode");
  if(node.id() == 1925746696 && postcodeValue)
  {
    std::cout << int(postcodeValue[0]) << std::endl;
    std::cout << int(postcodeValue[1]) << std::endl;
    std::cout << int(postcodeValue[2]) << std::endl;
    std::cout << int(postcodeValue[3]) << std::endl;
    std::cout << int(postcodeValue[4]) << std::endl;
    std::cout << int(postcodeValue[5]) << std::endl;
    std::cout << int(postcodeValue[6]) << std::endl;
    std::cout << int(postcodeValue[7]) << std::endl;
    std::cout << int(postcodeValue[8]) << std::endl;
    std::cout << int(postcodeValue[9]) << std::endl;
    std::cout << int(postcodeValue[10]) << std::endl;
  }
}

Then it still returns the negative values before a zero in the char*.

[joto]

The data is broken there. There is a U+200E character at the end of the postcode. Thats a Unicode left-to-right marker (http://www.decodeunicode.org/de/u+200e). This is very difficult to see, because in most cases it will not show up, you can't see it in a browser for instance. But you can download http://www.openstreetmap.org/api/0.6/node/1925746696 and might see it with "less 1925746696" for instance.
So, no Osmium error.