case:  auto X::operator<=>(const Y&) const = default;  Compiler generates all 6 comparison operators to compare X with Y (memberwise)  Advanced:  Non-defaulted (then you also need to write an arguments  printf()  Not safe, not extensible  Easier to read, no series of << insertion operators  Separation of format string and arguments  Easy to localize76 Text Formatting (std::format)  New in C++20: std::format()  Safe and extensible  Easy to read, no series of << insertion operators  Separation of format string and arguments  Positional arguments  Easy to localize  More performant