Convert binary to hexadecimal

Hexadecimal format of a number is a reduced binary format of this number. Use BinToHex function to convert binary to hexadecimal format.

function BinToHex(BinStr: string): string;
const
  BinArray: array[0..15, 0..1] of string =
    (('0000', '0'), ('0001', '1'), ('0010', '2'), ('0011', '3'),
     ('0100', '4'), ('0101', '5'), ('0110', '6'), ('0111', '7'),
     ('1000', '8'), ('1001', '9'), ('1010', 'A'), ('1011', 'B'),
     ('1100', 'C'), ('1101', 'D'), ('1110', 'E'), ('1111', 'F'));
var
  Error: Boolean;
  j: Integer;
  BinPart: string;
begin
  Result:='';

  Error:=False;
  for j:=1 to Length(BinStr) do
    if not (BinStr[j] in ['0', '1']) then
    begin
      Error:=True;
      ShowMessage('This is not binary number');
      Break;
    end;

  if not Error then
  begin
    case Length(BinStr) mod 4 of
      1: BinStr:='000'+BinStr;
      2: BinStr:='00'+BinStr;
      3: BinStr:='0'+BinStr;
    end;

    while Length(BinStr)>0 do
    begin
      BinPart:=Copy(BinStr, Length(BinStr)-3, 4);
      Delete(BinStr, Length(BinStr)-3, 4);
      for j:=1 to 16 do
        if BinPart=BinArray[j-1, 0] then
          Result:=BinArray[j-1, 1]+Result;
    end;
  end;
end;