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cintsize

Custom int size other than using <stdint.h>

How can you get a custom-sized integer data type? Is there any other answer than using <stdint.h> types like uint16_t and uint32_t and are these types platform-independent?

Solution

  • The answer is mostly No. <stdint.h> provides integers of specific sizes available on a given platform, but there's no standard way to get, say, a 20-bit integer but you can specify arbitrary size smaller than those provided by <stdint.h> by using bitfields. The following provides a 20-bit unsigned int that works as you would expect it to, though the interface is a little clunky.

    struct uint20_s {
   unsigned int val : 20;
};

    Broadly speaking it is non-trivial to implement integer semantics for word-sizes larger than those supported by the underlying hardware. There is an entire class of libraries dedicated to working with arbitrary precision numerics.