sizeof (integral types)

[Richard Sargent]

gwyn at smoke.BRL.MIL (Doug Gwyn) in Message-ID: <10044 at smoke.BRL.MIL> writes:
> 
> In article <12005 at paris.ics.uci.edu> Doug Schmidt <schmidt at glacier.ics.uci.edu> writes:
> >I realize the relation short <= int <= long holds, I'm just curious
> >whether there is any minimum that these basic types must meet (e.g.,
> >short >= 16 bits, etc.).
> 
> chars are at least 8 bits,
> shorts are at least 16 bits,
> longs are at least 32 bits.

I quote from the ANSI C DRAFT dated January 11, 1988, Section 3.1.2.5:

   An object declared as type  char  is large enough to store any member
   of the basic execution character set.  ...

   There are four _signed integer types_, designated as  signed char,
   short int,  int,  and  long int.  ...

   ...  A "plain"  int  object has the natural size SUGGESTED by the
   architecture of the execution environment ( ... in the header <limits.h>).
   In the list of signed integer types above, the range of values of each
   type is a subrange of the values of the next type in the list.

Please note that this definition explicitly avoids any claims about the sizes
of the types except for the "<=" business in the first message.  It most
definitely does NOT say anything about 8, 16, or 32 bits!  In fact, the
definition permits implementations of 8 bit longs and others of 32 bit chars!
(Of course, no one in their right mind would try to sell such a product,
but it is not forbidden by the language definition.)

Richard Sargent
Systems Analyst