如何比较两个数组，然后为'matches'添加一个类到从新数组生成的输出选择选项？

I have an array of all options that will be in a select box:

Array
(
   [2836] => 4 16:40:00
   [2835] => 3 13:20:00
)

There is a second array of options that have a particular flag in the DB:

Array
(
   [2835] => 3 13:20:00
)

How can I compare these two arrays to generate a select list that applies a particular class to the matches found in the arrays? I'd love some help thanks!

The view for my select list which receives the first array:

<select>
<?php foreach ($courses as $key=>$course): ?>   
<option id="<?php echo $key;?>">        
    <?php echo $course; ?>
</option>
<?php endforeach;?> 
</select>

You can use array_intersect to find those values common for both arrays. Then in your foreach loop you can check if the current key (or value) is from matches array.

$matches = array_intersect($arr1, $arr2);

In the view file:

<select>
<?php foreach ($courses as $key=>$course): ?>   
    <option id="<?php echo $key;?>" class="<?php echo isset($matches[$key]) ? 'match' : '' ?>">        
        <?php echo $course; ?>
    </option>
<?php endforeach;?> 
</select>