php - Invalid argument when passing checkbox array from GET to POST -

php novice here. goal to:

a) display table of booking options (fitness classes) dynamically database records, allow user select multiple options checkboxes against each row - bit's working.

b) pass checkbox selection table listing selected data on confirmation page. i'm getting error here: invalid argument supplied foreach().

c) update database when user hits second page's 'confirm' button.

research far uncovered this advice on using $_get , $_post achieve array.

my checkbox code on initial page:

    echo '<form action="makebooking.php" method="get">';     echo '<td><input type="checkbox" name="class_id[]" value=' . $row['class_id'] . '</td></tr>'; 

the foreach statement error comes code generates table of choices on second page:

    //check if set classes.php      if (isset($_get['class_id'])) {     // grab score data     foreach($_get['class_id'] $class_id) {       $_get['class_id'] = $class_id;         }      }     //table header     echo '<table class="table table-bordered table-hover">';     echo '<thead><tr><th>date</th><th>time</th><th>venue</th><th>who\'s going?</th>                                            <th>add someone</th></tr></thead>';        //create form       echo '<form method="post" action="' . $_server['php_self'] . '">';        //get class ids use in post       foreach ($_get['class_id'] $class_id) {       $sql = "select class_id, date_format(date, '%a, %d %b') new_date,           date_format(time, '%h:%i') new_time, venue classes class_id = '$class_id'";       $data = mysqli_query($dbc, $sql);        //---------------------------------------------------------------------------------       //get table data           while ($row = mysqli_fetch_array($data)) {             $date = $row["new_date"];             $time = $row["new_time"];             $venue = $row["venue"];             $class_id = $row["class_id"];           } //---------------------------------------------------------------------------------       //show table of selected classes           echo '<input type="hidden" name="id" value= ' . $class_id . ' />';             echo '<td>' . $date . '</td>';             echo '<td>' . $time . '</td>';             echo '<td>' . $venue . '</td>';             echo '<td>' . $username . '</td>';             echo '<td><button class="btn btn-mini" type="button"><i class="icon-user"></i><i class="icon-plus"</i></button></td></tr>';       }        echo'</table>';           // make booking button             echo '<input type="submit" name="submit" class="btn btn-large btn-primary pull-right" value="confirm">';             echo '</form>';         } 

full code of both pages @ this pastebin. error-fixing advice gratefully accepted!

figured out had been declaring variables in if/else loops made them inaccessible other parts of code.

i added hidden input arrays both tables validate input. required string-to-integer conversion of class id in order update db selected data.

full fixed code here struggling similar.