From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=unavailable autolearn_force=no version=3.4.4 X-Received: by 10.36.83.132 with SMTP id n126mr2844477itb.11.1512082145986; Thu, 30 Nov 2017 14:49:05 -0800 (PST) X-Received: by 10.157.5.211 with SMTP id 77mr214053otd.0.1512082145904; Thu, 30 Nov 2017 14:49:05 -0800 (PST) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.org!news.kjsl.com!usenet.stanford.edu!193no201905itr.0!news-out.google.com!x87ni223ita.0!nntp.google.com!i6no207293itb.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Thu, 30 Nov 2017 14:49:05 -0800 (PST) In-Reply-To: <3ca6a682-9af1-40e3-a4ac-db739b38e4d7@googlegroups.com> Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=97.117.255.82; posting-account=x5rpZwoAAABMN2XPwcebPWPkebpwQNJG NNTP-Posting-Host: 97.117.255.82 References: <0b6bd27e-e9ec-4854-bbb1-85e1d9ac92e1@googlegroups.com> <227d5a7f-6d5b-4b76-ac31-7d15bb6dc284@googlegroups.com> <16c980c2-1fa6-4084-97ea-b576c75b99c3@googlegroups.com> <3ca6a682-9af1-40e3-a4ac-db739b38e4d7@googlegroups.com> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <250a0542-f568-41d3-9e09-9d5ada8cb638@googlegroups.com> Subject: Re: How to access an array using two different indexing schemes From: Jerry Injection-Date: Thu, 30 Nov 2017 22:49:05 +0000 Content-Type: text/plain; charset="UTF-8" Xref: reader02.eternal-september.org comp.lang.ada:49285 Date: 2017-11-30T14:49:05-08:00 List-Id: On Thursday, November 30, 2017 at 4:11:05 AM UTC-7, AdaMagica wrote: > > Then try: > > procedure Do_Stuffs (Data: in out General_Real_Array) is > > subtype Indexing is General_Real_Array (1..Data'Length); > subtype Offset is General_Real_Array (0..Integer'Pred (Data'Length)); > > procedure Use_1_Based (X: in out Indexing) is separate; > procedure Use_0_Based (X: in out Offset ) is separate; > > begin > > Use_1_Based (Indexing (Data)); > Use_0_Based (Offset (Data)); > > end Do_Stuffs; I tried this: with Ada.Text_IO; use Ada.Text_IO; Procedure AdaMagica is Subtype Real is Float range Float'Range; -- Get rid of non-numeric. Type General_Real_Array is Array(Integer range <>) of Real; My_Data : General_Real_Array(0 .. 4) := (0.0, 1.0, 2.0, 3.0, 4.0); procedure Do_Stuffs (Data: in out General_Real_Array) is subtype Indexing is General_Real_Array (1..Data'Length); subtype Offset is General_Real_Array (0..Integer'Pred (Data'Length)); procedure Use_1_Based (X: in out Indexing) is begin for i in X'range loop X(i) := X(i) + 0.1; Put_Line(i'img & " " & X(i)'img); end loop; end Use_1_Based; procedure Use_0_Based (X: in out Offset) is begin for i in X'range loop X(i) := X(i) + 0.2; Put_Line(i'img & " " & X(i)'img); end loop; end Use_0_Based; begin Use_1_Based (Indexing (Data)); New_Line; Use_0_Based (Offset (Data)); end Do_Stuffs; Begin Do_Stuffs(My_Data); End AdaMagica; Resulting in 1 1.00000E-01 2 1.10000E+00 3 2.10000E+00 4 3.10000E+00 5 4.10000E+00 0 3.00000E-01 1 1.30000E+00 2 2.30000E+00 3 3.30000E+00 4 4.30000E+00 At the subprogram level that you have devised, this works. However: * It requires a two-level subprogram construction to achieve the result, requiring a wrapper procedure to set things up; * Does not result in a view conversion (or whatever you want to call it) at the main program level or at the subprogram level, and thus; * Does not allow the dual indexing scheme. I believe Randy showed how to accomplish the type conversion at the subroutine level a few days ago in this thread, also including the case where the array is allocated with access variables. Jerry