Why would uint32_t be preferred rather than uint_fast32_t?

Question

It seems that uint32_t is much more prevalent than uint_fast32_t (I realise this is anecdotal evidence). That seems counter-intuitive to me, though.

Answer 1

I have not seen evidence that uint32_t be used for its range. Instead, most of the time that I've seen uint32_t is used, it is to hold exactly 4 octets of data in various algorithms, with guaranteed wraparound and shift semantics!

There are also other reasons to use uint32_t instead of uint_fast32_t: Often it is that it will provide stable ABI. Additionally the memory usage can be known accurately. This very much offsets whatever the speed gain would be from uint_fast32_t, whenever that type would be distinct from that of uint32_t.

For values < 65536, there is already a handy type, it is called unsigned int (unsigned short is required to have at least that range as well, but unsigned int is of the native word size) For values < 4294967296, there is another called unsigned long.

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And lastly, people do not use uint_fast32_t because it is annoyingly long to type and easy to mistype :D