comp.lang.c FAQ list · Question 1.3

Q: Since C doesn't define sizes exactly, I've been using typedefs like int16 and int32. I can then define these typedefs to be int, short, long, etc. depending on what machine I'm using. That should solve everything, right?

A: If you truly need control over exact type sizes, this is the right approach. There remain several things to be aware of:

There might not be an exact match on some machines. (There are, for example, 36-bit machines.)
A typedef like int16 or int32 accomplishes nothing if its intended meaning is ``at least'' the specified size, because types int and long are already essentially defined as being ``at least 16 bits'' and ``at least 32 bits,'' respectively.
Typedefs will never do anything about byte order problems (e.g. if you're trying to interchange data or conform to externally-imposed storage layouts).
You no longer have to define your own typedefs, because the Standard header <inttypes.h> contains a complete set.