php for a array of a array

Question

I have an html form that passes an array into php and then does a for loop to print out values. This is the code that I have

$payloads = $_POST['topay'];
$loadNum = $_POST['loadnum'];
$unit = $_POST['unit'];
$driver = $_POST['driver'];

for($i=0;$i<count($payloads);$i++)
    {
        echo $payloads[$i];
        echo "<br>";
        echo '<td width="50" valign="top">'.$loadNum[$i].'</td>';
        echo '<td width="50" valign="top">'.$unit[$i].'</td>';
        echo '<td width="150" valign="top">'.$driver[$i].'</td>';
    }

the $_POST['topay'] is a checkbox array that I pass in where only the items that are checked will come through. For example in the form that I pass to php there are multiple check boxes, and it should only pass the ones that are checked. When I do the first echo in the for loop it correctly prints out the values, but the echos within the do not.

Values:

$loadNum = [5,6]
$unit = [101,103]
driver = ["joe", "mike"]

When both of these checkboxes are checked, the output works correctly. When the first checkbox is checked, the output works correctly. However, if I only check the second one (6, 103, "mike"), the output still comes out for (5,101,"joe")

EDIT: here is the HTML code that i send to this php page:

echo '<form action="statement.php" target="_blank" METHOD="post">';
echo '<td><input type="checkbox" name="topay[]" value="'.$loadNumber.'" checked></td>';
echo '<td width="70"><input type="hidden" name="loadnum[]" value="'.$loadNumber.'" />'. $loadNumber.'</td>';
echo '<td width="70"><input type="hidden" name="unit[]" value="'.$unit.'" />' .$unit.'</td>';
echo '<td width="150"><input type="hidden" name="driver[]" value="'.$driver.'" />' .$driver.'</td>';
?>
<p><input type="submit" name="sumbit" value="Create Statement" /></p>

Answer 1

Assuming you have properly named the input values, e.g.:

<input name="topay[0]" type="checkbox">
<input name="loadnum[0]" value="5">
<input name="unit[0]" value="101">
<input name="driver[0]" value="joe">

<input name="topay[1]" type="checkbox">
<input name="loadnum[1]" value="6">
<input name="unit[1]" value="103">
<input name="driver[1]" value="mike">

Take note of the topay[0] and topay[1] notation that I'm using, as opposed to your form input values that use topay[]:

<input type="checkbox" name="topay[]" value=" ...
<input type="hidden" name="loadnum[]" ...
<input type="hidden" name="unit[]" ...

Checkbox field values are only sent at form submission if they're checked, so this will be sent:

• If only the first checkbox is checked -> [5]
• If both checkboxes are checked -> [5, 6]
• If only the second checkbox is checked -> [6]

Using the naming scheme I've suggested earlier, this would be sent:

• If only the first checkbox is checked -> [5]
• If both checkboxes are checked -> [5, 6]
• If only the second checkbox is checked -> [1 => 6]

With those field names corrected, you should iterate the $payloads array using foreach so that you can get the associative key out as well; this is important, because only checked values are sent with the form.

foreach ($payloads as $key => $payload) {
    echo $payload, '<br>';
    printf('<td width="50" valign="top">%s</td>', $loadNum[$key]);
    printf('<td width="50" valign="top">%s</td>', $unit[$key]);
    printf('<td width="50" valign="top">%s</td>', $driver[$key]);
}