On #1: Signed under and overflow in C and C++ is undefined behaviour and can do weird things. In combination with compiler optimizations especially, the compile

On #1: Signed under and overflow in C and C++ is undefined behaviour and can do weird things. In combination with compiler optimizations especially, the compiler can simply assume it never happens. Using unsigned types means when someone passes you a negative int at least the result is well-defined and can be debugged when your program explodes. Use unsigned types for unsigned values, and ensure all (new at least) code compiles cleanly with -Wconversion and -Wsign-conversion enabled, which should really be the default warning level these days.