Hey Meiqin,

There is already a better version proposed by Tiago Freire at
https://wg21.link/P3161R2 which adds a much more C++-like version of
checked integer arithmetic.

By all means, C++ developers should have an idiomatic interface to do
these things, with references instead of pointers. <stdckdint.h> makes
sense to have for C compatibility alone.