checkbox filled with database data in php

I have this code that creates the calendar and checkboxes:

<?php

# PHP Calendar (version 2.3), written by Keith Devens

function generate_calendar($year, $month, $days = array(), $day_name_length = 3, $month_href = NULL, $first_day = 0, $pn = array()){
    $first_of_month = gmmktime(0,0,0,$month,1,$year);

    #remember that mktime will automatically correct if invalid dates are entered
    # for instance, mktime(0,0,0,12,32,1997) will be the date for Jan 1, 1998
    # this provides a built in "rounding" feature to generate_calendar()

    $day_names = array(); #generate all the day names according to the current locale
    for($n=0,$t=(3+$first_day)*86400; $n<7; $n++,$t+=86400) #January 4, 1970 was a Sunday
        $day_names[$n] = ucfirst(gmstrftime('%A',$t)); #%A means full textual day name

        $mes_pt = array('', 'Janeiro', 'Fevereiro', 'Março', 'Abril', 'Maio', 'Junho', 'Julho', 'Agosto', 'Setembro', 'Outubro', 'Novembro', 'Dezembro');

    list($month, $year, $month_name, $weekday) = explode(',',gmstrftime('%m,%Y,%B,%w',$first_of_month));
    $weekday = ($weekday + 7 - $first_day) % 7; #adjust for $first_day
    //$title   = htmlentities(ucfirst($month_name)).'&nbsp;'.$year;  #note that some locales don't capitalize month and day names

    $title   = htmlentities(ucfirst($mes_pt[(int)$month])).'&nbsp;'.$year;

    #Begin calendar. Uses a real <caption>. See http://diveintomark.org/archives/2002/07/03
    @list($p, $pl) = each($pn); @list($n, $nl) = each($pn); #previous and next links, if applicable
    if($p) $p = '<span class="calendar-prev">'.($pl ? '<a href="'.htmlspecialchars($pl).'">'.$p.'</a>' : $p).'</span>&nbsp;';
    if($n) $n = '&nbsp;<span class="calendar-next">'.($nl ? '<a href="'.htmlspecialchars($nl).'">'.$n.'</a>' : $n).'</span>';
    $calendar = '<table class="calendar">'."\n".
        '<caption class="calendar-month"><h1><center><strong>'.$p.($month_href ? '<a href="'.htmlspecialchars($month_href).'">'.$title.'</a>' : $title).$n."</strong></center></h1></caption>\n<tr>";

    if($day_name_length){ #if the day names should be shown ($day_name_length > 0)
        #if day_name_length is >3, the full name of the day will be printed
        //foreach($day_names as $d)
            //$calendar .= '<th abbr="'.htmlentities($d).'">'.htmlentities($day_name_length < 4 ? substr($d,0,$day_name_length) : $d).'</th>';

            $calendar .= "<th bgcolor='silver' align='center'>Domingo</th>";
            $calendar .= "<th bgcolor='silver' align='center'>Segunda</th>";
            $calendar .= "<th bgcolor='silver' align='center'>Terça</th>";
            $calendar .=  "<th bgcolor='silver' align='center'>Quarta</th>";
            $calendar .= "<th bgcolor='silver' align='center'>Quinta</th>";
            $calendar .= "<th bgcolor='silver' align='center'>Sexta</th>";
            $calendar .=  "<th bgcolor='silver' align='center'>Sábado</th>";

        $calendar .= "</tr>\n<tr>";
    }

    if($weekday > 0) $calendar .= '<td colspan="'.$weekday.'">&nbsp;</td>'; #initial 'empty' days
    for($day=1,$days_in_month=gmdate('t',$first_of_month); $day<=$days_in_month; $day++,$weekday++){
        if($weekday == 7){
            $weekday   = 0; #start a new week
            $calendar .= "</tr>\n<tr>";

        }
        if(isset($days[$day]) and is_array($days[$day])){
            @list($link, $classes, $content) = $days[$day];
            if(is_null($content))  $content  = $day;
            $calendar .= '<td'.($classes ? ' class="'.htmlspecialchars($classes).'">' : '>').
                ($link ? '<a href="'.htmlspecialchars($link).'">'.$content.'</a>' : $content).'</td>';
        }
        else 

        $calendar .= "<td bgcolor='#F5F5F5' align='center' data-semana=''><center><font size='2px'/>
        <input type='checkbox' name='DataRegisto[]' value='$year-$month-$day'> $year-$month-$day  <br />
        <input type='checkbox' name='Pequeno[]' value='Peq. Almoço'> Peq. Almoço <br />
        <input type='checkbox' name='Almoco[]' value='Almoço'> Almoço <br />
        <input type='checkbox' name='Dieta[]' value='Almoço Dieta'> Almoço (Dieta)<br />
        <input type='checkbox' name='Lanche[]' value='Lanche'> Lanche<br />
        <input type='checkbox' name='Jantar[]' value='Jantar'> Jantar<br />
        <input type='checkbox' name='JantarDie[]' value='Jantar Dieta'> Jantar (Dieta)</font></center></td>";

    }
    if($weekday != 7) $calendar .= '<td colspan="'.(7-$weekday).'">&nbsp;

    </td>'; #remaining "empty" days

    return $calendar."</tr>\n</table>\n";
}

    date_default_timezone_set('Europe/Lisbon');

    $dates = date('Y/m/d');
    $hoje = getdate(strtotime($dates)); 


    //Monta o calendário
    if(isset($_POST["data"])){
?>    
        <form name="form2" id="mainForm2" method="post" enctype="multipart/form-data" action="">    
            <?php
                list($dia, $mes, $ano) = explode('/', $_POST["data"]);
                echo generate_calendar($ano,$mes,$dia);
            ?>
            <input type="submit" name="registar" value="Marcar">
        </form>

    <?php } else { ?>

        <form name="form3" id="mainForm3" method="post"  action="">
            <?php  echo generate_calendar($hoje["year"], $hoje["mon"], $hoje["mday"]); ?>

            <input type="submit" name="registar" value="Marcar">
        </form>
    <?php } ?>

I use this code to insert into the database:

<?php 
if(isset($_POST['registar']))
{
for ($i=0;$i<count($_POST["DataRegisto"]);$i++) {
    $data = $_POST['DataRegisto'][$i];
    $pequeno = $_POST['Pequeno'][$i];
    $almoco = $_POST['Almoco'][$i];
    $dieta = $_POST['Dieta'][$i];
    $lanche = $_POST['Lanche'][$i];
    $jantar = $_POST['Jantar'][$i];
    $jantardie = $_POST['JantarDie'][$i];



        $sql="INSERT INTO testeteste (DataRegisto,Pequeno,Almoco,Dieta,Lanche,Jantar,JantarDie) VALUES ('$data','$pequeno','$almoco','$dieta','$lanche','$jantar','$jantardie')";

        $r = mysqli_query($conn,$sql);
}
}

?>

Now I want the checkboxes to be selected according to the data in the database table and for this I am using this code:

<?php 

$result_cursos = "SELECT DataRegisto,
       Pequeno,
       Almoco,
       Dieta,
       Lanche,
       Jantar,
       JantarDie

FROM centrodb.testeteste";
    $resultado_cursos = mysqli_query($conn, $result_cursos);

     foreach ($resultado_cursos as $row) {
          $data = $row['DataRegisto'];
          $pequeno = $row['Pequeno'];
          $almoco = $row['Almoco'];
          $dieta = $row['Dieta'];
          $lanche = $row['Lanche'];
          $jantar = $row['Jantar'];
          $jantardie = $row['JantarDie'];

          $marcado = '';
          if(in_array($data, $pequeno, $almoco, $dieta, $lanche, $jantar, $jantardie))
                $marcado = 'checked';    

          $option.='<label class="checkbox-inline"><input type="checkbox" name="DataRegisto[]" value="'.$data.'" ></label>';
      $option.='<label class="checkbox-inline"><input type="checkbox" name="Pequeno[]" value="'.$pequeno.'" ></label>';
      $option.='<label class="checkbox-inline"><input type="checkbox" name="Almoco[]" value="'.$almoco.'" ></label>';
      $option.='<label class="checkbox-inline"><input type="checkbox" name="Dieta[]" value="'.$dieta.'" ></label>';
      $option.='<label class="checkbox-inline"><input type="checkbox" name="Lanche[]" value="'.$lanche.'" ></label>';
      $option.='<label class="checkbox-inline"><input type="checkbox" name="Jantar[]" value="'.$jantar.'" ></label>';
      $option.='<label class="checkbox-inline"><input type="checkbox" name="JantarDie[]" value="'.$jantardie.'" ></label>';
    }
?>

But the code for showing selected checkboxes is not working.