<?php
    # Ok dit is uiteraard overbodig en kan veel korter
    '<select class="text_input_form" id="date_day_'.$printline4.'" name="date[day]">
    <option'; if($print_day==01){echo' selected="selected"';}echo' value="01">1</option>
    <option'; if($print_day==02){echo' selected="selected"';}echo' value="02">2</option>
    <option'; if($print_day==03){echo' selected="selected"';}echo' value="03">3</option>
    <option'; if($print_day==04){echo' selected="selected"';}echo' value="04">4</option>
    <option'; if($print_day==05){echo' selected="selected"';}echo' value="05">5</option>
    <option'; if($print_day==06){echo' selected="selected"';}echo' value="06">6</option>
    <option'; if($print_day==07){echo' selected="selected"';}echo' value="07">7</option>
    <option'; if($print_day==08){echo' selected="selected"';}echo' value="08">8</option>
    <option'; if($print_day==09){echo' selected="selected"';}echo' value="09">9</option>
    <option'; if($print_day==10){echo' selected="selected"';}echo' value="10">10</option>
    <option'; if($print_day==11){echo' selected="selected"';}echo' value="11">11</option>
    <option'; if($print_day==12){echo' selected="selected"';}echo' value="12">12</option>
    <option'; if($print_day==13){echo' selected="selected"';}echo' value="13">13</option>
    <option'; if($print_day==14){echo' selected="selected"';}echo' value="14">14</option>
    <option'; if($print_day==15){echo' selected="selected"';}echo' value="15">15</option>
    <option'; if($print_day==16){echo' selected="selected"';}echo' value="16">16</option>
    <option'; if($print_day==17){echo' selected="selected"';}echo' value="17">17</option>
    <option'; if($print_day==18){echo' selected="selected"';}echo' value="18">18</option>
    <option'; if($print_day==19){echo' selected="selected"';}echo' value="19">19</option>
    <option'; if($print_day==20){echo' selected="selected"';}echo' value="20">20</option>
    <option'; if($print_day==21){echo' selected="selected"';}echo' value="21">21</option>
    <option'; if($print_day==22){echo' selected="selected"';}echo' value="22">22</option>
    <option'; if($print_day==23){echo' selected="selected"';}echo' value="23">23</option>
    <option'; if($print_day==24){echo' selected="selected"';}echo' value="24">24</option>
    <option'; if($print_day==25){echo' selected="selected"';}echo' value="25">25</option>
    <option'; if($print_day==26){echo' selected="selected"';}echo' value="26">26</option>
    <option'; if($print_day==27){echo' selected="selected"';}echo' value="27">27</option>
    <option'; if($print_day==28){echo' selected="selected"';}echo' value="28">28</option>
    <option'; if($print_day==29){echo' selected="selected"';}echo' value="29">29</option>
    <option'; if($print_day==30){echo' selected="selected"';}echo' value="30">30</option>
    <option'; if($print_day==31){echo' selected="selected"';}echo' value="31">31</option>
    </select>';

    # Ik ga hier nu altijd van 31 uit, maar dit verschilt natuurlijk eigenlijk per maand, dat zou je ook in kunnen bouwen
    $days   = 31;
    $str    = '';
    $str   .= '<select class="text_input_form" id="date_day_' . $printline4 . '" name="date[day]">'

    for ( $i = 1; $i < ($days + 1); $i++; ) {
        $day = ($i < 10 ? '0' . $i : $i);

        $str .= '<option' . ($print_day == (int)$day ? ' selected="selected"' : '') . ' value="' . $day . '">' . $i . '</option>';
    }
    $str   .= '</select>';
?>