Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

function ReverseString1(const s: string): string;
 var
   i, len: Integer;
 begin
   len := Length(s);
   SetLength(Result, len);
   for i := len downto 1 do
   begin
     Result[len - i + 1] := s[i];
   end;
 end;

 function ReverseString2(const Str: string): string;
 // by Ido Kanner 
var
   ch: Char;
   i, Size: Integer;
 begin
   Result := Str;
   Size   := Length(Result);
   if (Size >= 2) then
   // 2 or more chars 
  begin
     // For 1 to middle of the string 
    for i := 1 to (Size div 2) do
     begin
       // Lets get the charecter of the current place in the string 
      ch := Result[i];
       // Place the Current pos of the char 
      // with the char of it's mirror place... 
      Result[i] := Result[Size - (i - 1)];
       // In the mirror place we will put char of the 
      // Original place... And we switched places !!! 
      Result[Size - (i - 1)] := ch;
     end
   end;
 end;


 function ReverseString3(S: string): string;
 // by Rudy Velthuis 
var
   P, Q: PChar;
   C: Char;
 begin
   Result := S;
   if Length(Result) = 0 then Exit;
   P := PChar(Result);
   Q := P + Length(Result) - 1;
   while P < Q do
   begin
     C := P^;
     P^ := Q^;
     Q^ := C;
     Inc(P);
     Dec(Q);
   end;
 end;

 procedure ReverseString4(var S: string);
 // by Rudy Velthuis 
var
   P, Q: PChar;
   C: Char;
 begin
   if Length(S) = 0 then Exit;
   P := PChar(S);
   Q := P + Length(S) - 1;
   while P < Q do
   begin
     C := P^;
     P^ := Q^;
     Q^ := C;
     Inc(P);
     Dec(Q);
   end;
 end;