From: Keith.S.Thompson+u@gmail.com   
      
   Thiago Adams  writes:   
   > Em 02/09/2025 17:10, Thiago Adams escreveu:   
   >> The type used by MSVC compiler seems not follow the C standard.   
   >> I choose the number 2147483648 that is the next number after max signed i32.   
   >   
   > For some reason GCC and clang have a warning (integer literal is too   
   > large to be represented in a signed integer type) only for decimal   
   > form.   
   >   
   > We have a warning for 18408377700990114895 but not for the same number   
   > written as hex 0xff77b1fcbebcdc4f.   
      
   Yes.   
      
   gcc's warning for 18408377700990114895 (which is slightly smaller   
   than 2**64) is "integer constant is so large that it is unsigned".   
   This is *incorrect* (and I think it's been reported as a bug), but   
   the incorrect wording of the warning is not a conformance issue.   
      
   (I'm assuming long long is 64 bits.  It can be wider, at least   
   theoretically.)   
      
   In C99 and later, an unsuffixed decimal constant is always of some   
   signed type, the smallest of int, long, and long long in which it   
   fits -- or of an extended integer type, but gcc doesn't have those.   
   Since 18408377700990114895 exceeds LLONG_MAX, it has no type, and   
   is a constraint violation. (In C90, the list was int, long, unsigned   
   long, which is the source of the wording of the warning message.)   
      
   An unsuffixed hex constant can be of type int, unsigned int, long   
   int, unsigned long int, long long int, or unsigned long long int   
   (or an extended integer type).  Since 0xff77b1fcbebcdc4f is greater   
   than LLONG_MAX and less than (or equal to) ULLONG_MAX, it's of type   
   unsigned long long int, and no diagostic is needed.   
      
   [...]   
      
   > But I don't think hex is especial in this case.   
      
   It is.   
      
   > unsigned long long u[] = {18408377700990114895 , 0xff77b1fcbebcdc4f};   
   >   
   > I think a suffix ULL maybe useful in this case.   
      
   This:   
      
   unsigned long long u[] = {18408377700990114895ULL, 0xff77b1fcbebcdc4fULL};   
      
   is valid.  The ULL suffix on the hex constant isn't strictly   
   necessary, but it certainly doesn't hurt.  (If unsigned long long is,   
   say, 128 bits and long is 64 bits, an unsuffixed 18408377700990114895   
   will be of type long long, and an unsuffixed 0xff77b1fcbebcdc4f   
   will be of type unsigned long, both of which will be implicitly   
   converted to unsigned long long.)   
      
   For that matter, just a "U" suffix would suffice.  A decimal constant   
   with a "U" suffix is of type unsigned int, unsigned long int, or   
   unsigned long long int.   
      
   See N1570 6.4.4.1 or N3220 6.4.4.2.   
      
   --   
   Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com   
   void Void(void) { Void(); } /* The recursive call of the void */   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)