Index vom x-tem gesetztem Bit

[samso]

Den Vorschlag von Aviator aufgenommen und erweitert:

Delphi-Quellcode:

program Project5;

{$APPTYPE CONSOLE}
{$R *.res}

uses
  System.SysUtils;

function CheckBit(const Value, BitNumber: Integer): Integer;
var
  i: Integer;
  Mask: Integer;
begin
  if (Value <> 0) then
  begin
    i := 0;
    Mask := 0;
    while true do
    begin
      if Mask = 0 then
        Mask := 1;
      if (Value and Mask) <> 0 then
      begin
        Inc(i);
        if (i = BitNumber) then
        begin
          Result := Mask;
          Break;
        end;
      end;
      Mask := Mask shl 1;
    end;
  end
  else
    Result := -1;
end;

begin
  try
    if CheckBit($2A, 3) = 32 then
      writeln('Test 1 - ok');
    if CheckBit($2A, 5) = 8 then
      writeln('Test 2 - ok');
    readln;
  except
    on E: Exception do
      writeln(E.ClassName, ': ', E.Message);
  end;
end.