Re: Substrings as argument to procedures/functions

[reinkor <reinkor@gmail.com>]

On Tuesday, April 12, 2016 at 11:02:03 AM UTC+2, Dmitry A. Kazakov wrote:
> On 12/04/2016 10:25, reinkor wrote:
> 
> > I believed that if a substring is an argument to a subroutine,
> > then its "range" would start at 1 (and not inherited from the calling program).
> > But this seems not to be the case.
> >
> > Given the following Ada source code:
> >
> > with Text_IO;
> > use  Text_IO;
> > procedure t3 is
> >     package Int_Io is new Text_IO.Integer_Io (Integer);
> >     use Int_Io;
> >     procedure string_test1(S : String) is
> >     begin
> >        New_Line;
> >        Put(" In string_test1: ");
> >        Put(S'First,4);
> >        Put(S'Last,4);
> >     end string_test1;
> >     Str : String := "ABCDEF";
> > begin
> >        string_test1(Str);
> >        string_test1(Str(3..5));
> > end t3;
> >
> > The second call to "string_test1" gives:
> >
> >   In string_test1:    3   5
> >
> > (at least on my computer).
> >
> > Is this correct? And in case, is it "good" ? :-)
> 
> Yes, it is good.
> 
> Consider a program that uses an index to walk through a string/array. 
> When you pass a substring of the string and an index into it (usually 
> in-out) down to a subprogram, then the index remains valid.
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de


But as far as I remember, several other program languages do not bring the initial indexing down to subroutines like this?  Anyway, one may for example copy strings in soubroutines if one really want to start indexing at one.

Sometimes I want the soubroutines not to "know" too much :-)