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Date: 17 Apr 92 20:00:20 GMT
From: wdl39!mab@ford-wdl1.arpa  (Mark A Biggar)
Subject: Re: loop indices
Message-ID: <1992Apr17.200020.26094@wdl.loral.com>
List-Id: <comp.lang.ada>

In article <70482@ut-emx.uucp> hasan@emx.utexas.edu (David A. Hasan) writes:
>Suppose I have a matrix manipulation routine which must
>loop over the elements of several different ARRAYs.
>My question stems from the observation that unless the
>ARRAYs have the same bounds on their indices, I won't
>be able to index into all of them using a single FOR-LOOP
>index. Consider this example: 
>   DECLARE
>      TYPE Vector IS ARRAY( Positive RANGE <> ) OF Integer;
>      p1 : CONSTANT Positive := 21;
>      p2 : CONSTANT Positive := 51;
>      size : Natural := 5;
>
>      v1 : Vector( p1 .. (p1+size-1) );
>      v2 : Vector( p2 .. (p2+size-1) );
>   BEGIN
>      FOR i IN 1..size LOOP
>         v2(i) := v1(i);      -------------------(!)
>      END LOOP;
>   END;
>Obviously, I'll have constraint error problems here.
>The problem is not solve, either, if I replace the FOR
>LOOP by 
>   FOR i IN v2'RANGE LOOP
>since the index *still* won't work in <v1>.

What's wrong with using:

	FOR i IN 1..size LOOP
	    v2(p1+i-1) := v2(p2+i-1);
	END LOOP;

or

	FOR i IN v2'RANGE LOOP
	    v2(i) := v1(i-p2+p1);
	END LOOP;


--
Mark Biggar
mab@wdl1.wdl.loral.com