C and C++ are not the same programming languages, and advice for C is not
necessarily appropriate for C++. We follow standard C++, which e.g., doesn't
include "#pragma once". As another example, C++ code usually doesn't use
printf-style formatting as in "%zu" due to its lack of type-safety.

Generally speaking, please be aware that massive code changes such as changing
all integer types has a significant cost in testing, maintenance, making merges
difficult etc., and we generally do not perform them without really being sure
that they have a large benefit.

https://matt.sh/howto-c

standard types in stdint.h
uintptr_t, ptrdiff_t
size_t - %zu
#pragma once , not #ifndef PROJECT_HEADERNAME