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 10.182.111.227 with SMTP id il3mr1372990obb.41.1381945349817; Wed, 16 Oct 2013 10:42:29 -0700 (PDT) X-Received: by 10.50.44.67 with SMTP id c3mr103015igm.13.1381945349767; Wed, 16 Oct 2013 10:42:29 -0700 (PDT) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!news.glorb.com!news-out.readnews.com!news-xxxfer.readnews.com!209.85.216.88.MISMATCH!i2no15988970qav.0!news-out.google.com!9ni45434qaf.0!nntp.google.com!i2no15988962qav.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Wed, 16 Oct 2013 10:42:29 -0700 (PDT) In-Reply-To: <5b59543c-7c48-4427-afc6-30289f6d8895@googlegroups.com> Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=129.59.203.122; posting-account=7Oy7OQoAAABhVYFOo553Cn1-AaU-bSfl NNTP-Posting-Host: 129.59.203.122 References: <1374ac32-0fb5-4589-a9a5-7740030fd3c6@googlegroups.com> <4bb47482-ccb9-4641-a702-2b2978100ff9@googlegroups.com> <5b59543c-7c48-4427-afc6-30289f6d8895@googlegroups.com> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <54aa8ad2-cd98-4f3e-bef9-494ddaefe4e9@googlegroups.com> Subject: Re: Passing a String to a C/C++ Subprogram (Special Case) From: Eryndlia Mavourneen Injection-Date: Wed, 16 Oct 2013 17:42:29 +0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Xref: news.eternal-september.org comp.lang.ada:17438 Date: 2013-10-16T10:42:29-07:00 List-Id: On Wednesday, October 16, 2013 12:32:36 PM UTC-5, Martin wrote: > On Tuesday, October 15, 2013 10:02:17 PM UTC+1, Eryndlia Mavourneen wrote= : >=20 > > On Tuesday, October 15, 2013 3:11:30 PM UTC-5, Adam Beneschan wrote: >=20 > >=20 >=20 > > > On Tuesday, October 15, 2013 12:54:18 PM UTC-7, Eryndlia Mavourneen w= rote: >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > > > I have a couple of strings that are bounded; that is, they are esse= ntially fixed-length strings, and I need to pass them as "in" parameters to= a subprogram that may or may not be written in C/C++. I don't really want= to hassle with the Interfaces packages for this, since the subprogram lang= uage is indefinite, and the strings are part of a package that many others = likely will want to use, and the strings most likely will be used as standa= rd Ada fixed-length strings. >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > > > Q: Is there any reason that I cannot just declare each of them in t= his way, assuming the subprogram is written in C/C++: >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > > > . . . >=20 > >=20 >=20 > > > > A_String : String (1 .. 30); >=20 > >=20 >=20 > > > > pragma Convention (C, A_String); >=20 > >=20 >=20 > > > > . . . >=20 > >=20 >=20 > > > > procedure C_Prog (C_String : in String); >=20 > >=20 >=20 > > > > pragma Import (Entity =3D> C_Prog, ...); >=20 > >=20 >=20 > > > > begin >=20 > >=20 >=20 > > > > C_Prog (C_String =3D> A_String); >=20 > >=20 >=20 > > > > . . . >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > > > and have it work properly? >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > > B.3(70) says, "An Ada parameter of an array type with component type = T, of any mode, is passed as a t* argument to a C function, where t is the = C type corresponding to the Ada type T." Since a String is defined as an a= rray of Character in Ada, this should cause a "char*" argument to be passed= . However, this is in a section marked "Implementation Advice", so there's= a possibility that a particular Ada compiler may not conform. You'll want= to check the Ada compiler manual and/or try it yourself and see what code = it generates. Note that this means the 'First and 'Last of the string para= meter won't be passed to the C routine. But it looks like you know that al= ready.=20 >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > >=20 >=20 > >=20 >=20 > > > -- Adam >=20 > >=20 >=20 > >=20 >=20 > >=20 >=20 > > Yes, Adam. Thank you. Of course, Annex B is optional anyway. lol >=20 > >=20 >=20 > > I guess you choose your poison. >=20 > >=20 >=20 > >=20 >=20 > >=20 >=20 > > -- Eryndlia Mavourneen (KK1T) >=20 >=20 >=20 >=20 >=20 > Annex B is part of the 'core language' - it isn't optional. Annex A and J= are also 'core'. The 'Special Needs Annex' sections are the 'optional' par= ts of the language. See 1.1.2 and 1.1.3. >=20 >=20 >=20 > -- Martin In the Ada95 LRM (I have to use Ada95.), in the introduction to Annex B (B = 2/3) it states: "Support for interfacing to any foreign language is option= al." -- Eryndlia Mavourneen (KK1T)