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Representing signed values in corresponding unsigned types

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Can all the values of a signed int be represented in an unsigned int (or 
signed long in an unsigned long, etc.)? If INT_MIN is now 0 and all values are
arithmetically increased by -INT_MIN, is it guaranteed that every signed
value can be represented? In other words: is UINT_MAX >= INT_MAX - INT_MIN?

It seems obvious, but the standard appears to imply that this is not
guaranteed. It states:

>6.2.5.6
>
>For each of the signed integer types, there is a corresponding (but
>different) unsigned integer type that uses the same amount of storage 
>(including sign information) and has the same alignment requirements.

So, same amount of storage including sign bit implies UINT_MAX == INT_MAX*2

But:

>6.2.6.2
>
>For unsigned integer types, the bits of the object representation shall be
>divided into two groups: value bits and padding bits.
>[...]
>For signed integer types, the bits of an object representation shall be
>divided into three groups: value bits, padding bits and the sign bit. [...]
>(if there are M value bits in the signed type and N in the unsigned type,
>then M <= N).

But shouldn't it be M < N? Otherwise, if M == N, there are the same amount of
value bits in both signed and unsigned (implying the unsigned has more
padding bits), and UINT_MAX == INT_MAX. I doubt that this is ever done,
but the standard seems to permit it.

Although "The range of nonnegative values of a signed integer type is a 
subrange of its corresponding unsigned integer type" [6.2.5.9] the use of
'subrange' implies that M < N?


So, is it actually portable to represent signed integers as unsigned?

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Representing signed values in corresponding unsigned types NS <ns@2b.here> - 2026-06-28 10:11 +0000
  Re: Representing signed values in corresponding unsigned types ram@zedat.fu-berlin.de (Stefan Ram) - 2026-06-28 12:07 +0000
  Re: Representing signed values in corresponding unsigned types Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-06-28 06:52 -0700
    Re: Representing signed values in corresponding unsigned types Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-06-28 18:27 -0700
      Re: Representing signed values in corresponding unsigned types cross@spitfire.i.gajendra.net (Dan Cross) - 2026-06-29 12:13 +0000
      Re: Representing signed values in corresponding unsigned types Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-08-15 02:19 -0700
        Re: Representing signed values in corresponding unsigned types Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-15 05:48 -0700
  Re: Representing signed values in corresponding unsigned types James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-06-28 22:23 -0400
    Re: Representing signed values in corresponding unsigned types Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-06-28 20:24 -0700

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