RosettaCodeData/Task/Rep-string/Ada/rep-string.ada

32 lines
944 B
Ada

with Ada.Command_Line, Ada.Text_IO, Ada.Strings.Fixed;
procedure Rep_String is
function Find_Largest_Rep_String(S:String) return String is
L: Natural := S'Length;
begin
for I in reverse 1 .. L/2 loop
declare
use Ada.Strings.Fixed;
T: String := S(S'First .. S'First + I-1); -- the first I characters of S
U: String := (1+(L/I)) * T; -- repeat T so often that U'Length >= L
begin -- compare first L characers of U with S
if U(U'First .. U'First + S'Length -1) = S then
return T; -- T is a rep-string
end if;
end;
end loop;
return ""; -- no rep string;
end Find_Largest_Rep_String;
X: String := Ada.Command_Line.Argument(1);
Y: String := Find_Largest_Rep_String(X);
begin
if Y="" then
Ada.Text_IO.Put_Line("No rep-string for """ & X & """");
else
Ada.Text_IO.Put_Line("Longest rep-string for """& X &""": """& Y &"""");
end if;
end Rep_String;