Union type conversions

[Joseph Nathan Hall]

In article <19845 at watmath.waterloo.edu> atbowler at watmath.waterloo.edu (Alan T. Bowler [SDG]) writes:
 Actually I dn't think you are guaranteed anything more than
 if you assign to a particular union member you can get back the
 value you assigned by naming that member provided that you do
 no assign to any other member.  It is usual practice for a compiler
 to put all members of a union at the same starting address
 (i.e. equivalence them) however, there is no guarantee that
 the compiler does not simply do the equivalent of
 #define union struct
 and proceed from there.  Using union for a "pun" operation
...

Sorry, you're just plain wrong here.  From page 140 of K&R, I quote:

	"In effect, a union is a structure in which all members have
	 OFFSET ZERO [emphasis added], the structure is big enough to hold
	 the 'widest' member, and the alignment is appropriate for all
	 of the types in the union ..."
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