Beware: Hackers

Alan S. Driscoll alan at allegra.UUCP
Mon Jan 9 05:38:19 AEST 1984

>From Roger Ferrel:

	What we see here with the:

		inttype *= 0.5;
		inttype = inttype * 0.5;

	is a weakness of most C compilers. It seems none of them handles
	float operations very well when there are mixed types.  Of course
	the above is a poor example since normally more efficent code would
	be generated by using:

	inttype >>= 1;  /* how is this for getting off the subject? */

>From the C Reference Manual:

	The value of E1>>E2 is E1 right-shifted E2 bits.  The right shift
	is guaranteed to be logical (0-fill) if E1 is unsigned; otherwise
	it may be arithmetic (fill by a copy of the sign bit).

If the shift is logical, then negative values of "inttype" will give you
interesting results.

	Alan S. Driscoll
	AT&T Bell Laboratories

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