std::string Box::to_string(void)
{
// ähnlich wie StringBuffer in Java
std::ostringstream strbuf;
strbuf << "Box: Länge = ";
strbuf << length;
strbuf << ", Breite = ";
strbuf << width;
strbuf << ", Name = \"";
strbuf << name;
strbuf << "\"";
return strbuf.str();
}