int str2x(const std::string & str, long long & x);
int str2x(const std::string & str, unsigned long long & x);
//-----------------------------------------------------------------------------
const std::string & x2str(unsigned x, std::string & s);
int str2x(const std::string & str, long long & x);
int str2x(const std::string & str, unsigned long long & x);
//-----------------------------------------------------------------------------
const std::string & x2str(unsigned x, std::string & s);