int - Is there a general way in C to make a number greater than 64 bits or smaller than 8 bits?

Question

First of all, I am aware that what I am trying to do might be outside the C standard.

I'd like to know if it is possible to make a uint4_t/int4_t or uint128_t/int128_t type in C.

I know I could do this using bitshifts and complex functions, but can I do it without those?

Answer 1

Individual storage units (bytes) are no less than CHAR_BITS bits wide¹; even if you create a struct with a single 4-bit bitfield, the associated object will always take up a full storage unit.

There are multiple precision libraries such as GMP that allow you to work with values that can't fit into 32 or 64 bits. Might want to check them out.

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^{8 bits minimum, but may be wider.}