· No function should do anything if an error has already occurred.
· On error, a value of 0, nullptr, {}, etc., should be returned.
· Values shouldn't have overloaded meanings (eg. index or found).
· Values that are never used should not be returned at all.
Some of this code was originally written as C code and some of this code
was originally written as C++ code but made to resemble the then already
existing code that had once been C code. Changing it all to normal C++
now will make it easier and safer to work with going forward.
· Use unnamed namespace instead of static.
· Use reference instead of non-nullable pointer.
· Use bool instead of UBool.
· Use constexpr for static data.
· Use U_EXPORT instead of U_CAPI or U_CFUNC.
· Use the default calling convention instead of U_EXPORT2.
This is the normal standard way in C, C++ as well as Java and there's no
longer any reason for ICU to be different. The various internal macros
providing custom boolean constants can all be deleted and code as well
as documentation can be updated to use lowercase true/false everywhere.
