Extract file extension: Difference between revisions

==={{header|As originally specified}}===

==={{header|In response to problem discussions}}===

<lang Ada>with Ada.Text_IO; use Ada.Text_IO;

with Ada.Strings.Fixed; use Ada.Strings.Fixed;

use Ada.Strings;

with Ada.Characters.Handling; use Ada.Characters.Handling;

procedure Main is

function extension (S : in String) return String is

P_Index : Natural;

begin

P_Index :=

Index (Source => S, Pattern => ".", From => S'Last, Going => Backward);

if P_Index < 2 or else P_Index = S'Last then

return "";

else

for C of S (P_Index + 1 .. S'Last) loop

if not Is_Alphanumeric (C) then

return "";

end if;

end loop;

return S (P_Index .. S'Last);

end if;

end extension;

F1 : String := "http://example.com/download.tar.gz";

F2 : String := "CharacterModel.3DS";

F3 : String := ".desktop";

F4 : String := "document";

F5 : String := "document.txt_backup";

F6 : String := "/etc/pam.d/login:";

F7 : String := "filename.";

F8 : String := ".";

begin

Put_Line (F1 & " -> " & extension (F1));

Put_Line (F2 & " -> " & extension (F2));

Put_Line (F3 & " -> " & extension (F3));

Put_Line (F4 & " -> " & extension (F4));

Put_Line (F5 & " -> " & extension (F5));

Put_Line (F6 & " -> " & extension (F6));

Put_Line (F7 & " -> " & extension (F7));

Put_Line (F8 & " -> " & extension (F8));

end Main;

</lang>

{{output}}

<pre>

http://example.com/download.tar.gz -> .gz

CharacterModel.3DS -> .3DS

.desktop ->

document ->

document.txt_backup ->

/etc/pam.d/login: ->

filename. ->

. ->

</pre>