> int is cross-platform and forward compatible whereas uint32_t, uint64_t, uint8_t, uint16_t, etc. will all always be unsigned within a specified bound, so when

> int is cross-platform and forward compatible whereas uint32_t, uint64_t, uint8_t, uint16_t, etc. will all always be unsigned within a specified bound, so whenever we have 128-bit or 256-bit registers, we'll have to go back and update all this code uintN_t (and intN_t) are MORE portable and cross platform than int in the sense that you get much better guarantees about it's size and layout. Furthermore, int is NOT the size of the register (x64 commonly has an int of 32 bits) so any updating you'd have to do to uintN_t, you'd have to do to int as well. Regardless, I can't imagine why you'd need to do any updating in the first place - it's perfectly valid to stick a uint32_t in a 64 bit register. > nevermind the fact that int is usually more optimized than uint these days Where are ints more optimized than uint? Not in the processor, not in the compiler (modulo undefined behavior on overflow) and not in libraries.