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From: siegel@world.std.com (Rich Siegel)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Type cast problem in TP 3.0
Message-ID: <1991May3.024115.9562@world.std.com>
Date: 3 May 91 02:41:15 GMT
References: <11271@ncar.ucar.edu>
Distribution: na
Organization: Symantec Language Products Group
Lines: 25

In article <11271@ncar.ucar.edu> hpoppe@ncar.ucar.edu (Herb Poppe) writes:
>The TP 3.0 program below illustrates a problem I am having with type 
>casting that is driving me nuts. A set of 0..7 has a size of 1. A 
>SignedByte has a size of 1. Yet when I type cast the set of 0..7 to a 
>SignedByte the compiler complains that:
>
>"Expression can't be cast to the specified type."
>
>How do I interpret the bits in a set of 0..7 as a byte?

	In standard Pascal, casts to or from set-types are illegal. However,
a pointer cast can be used to effect the necessary result:

	s : set of 0..7;
	b : SignedByte;

	b := Ptr(@s)^;	{ recall that the "Ptr" type points to a SignedByte. }

R.

-- 
-----------------------------------------------------------------------
Rich Siegel                              Internet: siegel@world.std.com
Software Engineer                        Applelink: SIEGEL
Symantec Languages Group