Thread: typedef and portability

Look into <stdint.h>

The point is that, assuming that you are compiling with respect to C99 or later, or your compiler has it as a standard library extension, then you should consider using typedefs from <stdint.h>:

Originally Posted by C11 Clause 7.20.1.1 Exact-width integer types

The typedef name intN_t designates a signed integer type with width N, no padding bits, and a two's complement representation. Thus, int8_t denotes such a signed integer type with a width of exactly 8 bits.

The typedef name uintN_t designates an unsigned integer type with width N and no padding bits. Thus, uint24_t denotes such an unsigned integer type with a width of exactly 24 bits.

These types are optional. However, if an implementation provides integer types with widths of 8, 16, 32, or 64 bits, no padding bits, and (for the signed types) that have a two's complement representation, it shall define the corresponding typedef names.

So, you don't have to "mention __WORDSIZE to be some value either 32 bit or 64 bit", and in fact __WORDSIZE is some implementation defined name that will likely cause you a compile error except for the particular implementation that you investigated. Rather, the standard library implementation, if applicable, will provide the typedefs for you. Hence, instead of defining your own UINT16_T, you would just #include <stdint.h> and use uint16_t.