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 10.50.61.242 with SMTP id t18mr9837890igr.3.1381867890910; Tue, 15 Oct 2013 13:11:30 -0700 (PDT) X-Received: by 10.50.80.78 with SMTP id p14mr530925igx.6.1381867890842; Tue, 15 Oct 2013 13:11:30 -0700 (PDT) Path: border1.nntp.ams.giganews.com!nntp.giganews.com!newsfeeder.ewetel.de!newsfeed.kamp.net!newsfeed.kamp.net!nx02.iad01.newshosting.com!newshosting.com!69.16.185.11.MISMATCH!npeer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!i2no14450009qav.0!news-out.google.com!9ni44722qaf.0!nntp.google.com!i2no14449999qav.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Tue, 15 Oct 2013 13:11:30 -0700 (PDT) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=66.126.103.122; posting-account=RxNzCgoAAACA5KmgtFQuaU-WaH7rjnAO NNTP-Posting-Host: 66.126.103.122 References: User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <1374ac32-0fb5-4589-a9a5-7740030fd3c6@googlegroups.com> Subject: Re: Passing a String to a C/C++ Subprogram (Special Case) From: Adam Beneschan Injection-Date: Tue, 15 Oct 2013 20:11:30 +0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Received-Bytes: 2991 Date: 2013-10-15T13:11:30-07:00 List-Id: On Tuesday, October 15, 2013 12:54:18 PM UTC-7, Eryndlia Mavourneen wrote: > I have a couple of strings that are bounded; that is, they are essentiall= y fixed-length strings, and I need to pass them as "in" parameters to a sub= program that may or may not be written in C/C++. I don't really want to ha= ssle with the Interfaces packages for this, since the subprogram language i= s 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 standard Ada= fixed-length strings. >=20 >=20 >=20 > Q: Is there any reason that I cannot just declare each of them in this wa= y, assuming the subprogram is written in C/C++: >=20 >=20 >=20 > . . . > A_String : String (1 .. 30); > pragma Convention (C, A_String); > . . . > procedure C_Prog (C_String : in String); > pragma Import (Entity =3D> C_Prog, ...); > begin > C_Prog (C_String =3D> A_String); > . . . >=20 > and have it work properly? 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 array o= f Character in Ada, this should cause a "char*" argument to be passed. How= ever, this is in a section marked "Implementation Advice", so there's a pos= sibility that a particular Ada compiler may not conform. You'll want to ch= eck the Ada compiler manual and/or try it yourself and see what code it gen= erates. Note that this means the 'First and 'Last of the string parameter = won't be passed to the C routine. But it looks like you know that already.= =20 -- Adam