Re: Reading environment variables in ADA?

[gisle@krake.ii.uib.no (Gisle S{lensminde)]

In article <6tdl75$qs6$2@nyheter.chalmers.se>, Stefan Lingdell wrote:
>How do you read environment variables in ADA? I'm
>programming under UNIX (SunOS) if that makes any
>difference.
>
>Thanks,
>Stefan
>

There is packages to access environment variables and other OS things.
Since this is a posix feature, you can use the florist package, If have
thought to use a lot of OS features, that is a good idea. If not, you
can use the C interface. The program under reads the HOME
environment variable, and demonstrates how the C interface can be used
for this. I have tested it for solaris/gnat, but should work on all
Unix systems. If you use other compilers than GNAT, you maybe must 
link with the C library.  

The example:

with Interfaces.C.Strings;  
use type Interfaces.C.Strings.Chars_Ptr;
with Ada.Text_IO; use Ada.Text_IO;

procedure env is 

   package Cstr renames Interfaces.C.strings;

   function Getenv(Name : Cstr.Chars_Ptr) return Cstr.Chars_Ptr; 
   pragma Import(C, Getenv);

   Var_Name, Result : Cstr.Chars_Ptr;

begin
   Var_Name := Cstr.New_String("HOME");
   Result := Getenv(Var_Name);
   Cstr.Free(Var_Name);
   if Result /= Cstr.Null_Ptr then
      Put_Line(Cstr.Value(Result));
   end if;
end;
 

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  Gisle S�lensminde                Tlf:   55 34 07 63
  Eliasmarken 16                   
  5031 Laksev�g                    epost: gisle@ii.uib.no   

  UNIX is user friendly. It's just selective about who its friends are.
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