The Dangers of sizeof

[Richard Sargent]

acu at mentor.cc.purdue.edu (Floyd McWilliams) wrote in article 
<2280 at mentor.cc.purdue.edu>:

> In article <105 at servio.UUCP> penneyj at servio.UUCP (D. Jason Penney) writes:
> 
> [Discussion of how "sizeof (char) - 1" is 1 not 0.]
> 
> 	Oh really?  Then take a look at this:
> 
> --
> [Script to prove it ain't so.]
> --
> 
> 	"sizeof" may not be a function, but it does have a high precedence
> (it's a unary operator).  If what you posted were true, then everyone who
> tried a "sizeof(foo) + CONST" under pre-ANSI standard C would have been
> screwed; C didn't have a unary plus.
> 

Quite right!  I quote K&R, Section 7.2 Unary Operators, pages 187-188
(first edition).  The very last paragraph of the section, on page 188,
reads:

   "The construction  sizeof( type )  is taken to be a unit, so the
    expression  sizeof( type ) - 2  is the same as  (sizeof( type )) - 2."

QED.
Richard Sargent
Systems Analyst