魔力封包数字通讯之62进制

function c10to62(iDex: integer): string;
var
  s: array[0..61] of string;
  i: integer;
begin
  for i := 0 to 9 do
    s[i] := inttostr(i);
  for i := 10 to 35 do
  begin
    s[i] := chr(i + 87);
  end;
  for i := 36 to 61 do
  begin
    s[i] := chr(i + 29);
  end;
  result := '';
  while iDex <> 0 do
  begin
    result := s[iDex mod 62] + result;
    iDex := iDex div 62;
  end;
end;

function c62to10(s62: string): integer;
var
  s: array[0..61] of string;
  i, j: integer;
  sTmp: string;
  nTmp: integer;
begin
  for i := 0 to 9 do
    s[i] := inttostr(i);
  for i := 10 to 35 do
  begin
    s[i] := chr(i + 87);
  end;
  for i := 36 to 61 do
  begin
    s[i] := chr(i + 29);
  end;
  result := 0;
  for i := 1 to length(s62) do
  begin
    sTmp := copy(s62, (i), 1);
    nTmp := -1;
    for j := 0 to 61 do
      if s[j] = sTmp then
      begin
        nTmp := j;
        break;
      end;
    if nTmp = -1 then
    begin
      result := -1;
      exit;
    end;
    result := result * 62 + nTmp;
  end;
end;