Comparing an array against itself
<p>I am currently a bit stuck in finding out how to compare these variables against eachother, I have 24 dropdown selections with 24 options to choose from within each one, I then post them to the PHP page. What is the easiest, most efficient way of comparing each of these values against each other to check that each option that is chose is different from each other as none of the 24 options can be the same. I know that an array is the way forward with this, just not sure on how to compare them.
Any help is much appreciated.</p>

<pre><code>    $id = $_POST[trackid];
    $pos1 = $_POST[pos1];
    $pos2 = $_POST[pos2];
    $pos3 = $_POST[pos3];
    $pos4 = $_POST[pos4];
    $pos5 = $_POST[pos5];
    $pos6 = $_POST[pos6];
    $pos7 = $_POST[pos7];
    $pos8 = $_POST[pos8];
    $pos9 = $_POST[pos9];
    $pos10 = $_POST[pos10];
    $pos11 = $_POST[pos11];
    $pos12 = $_POST[pos12];
    $pos13 = $_POST[pos13];
    $pos14 = $_POST[pos14];
    $pos15 = $_POST[pos15];
    $pos16 = $_POST[pos16];
    $pos17 = $_POST[pos17];
    $pos18 = $_POST[pos18];
    $pos19 = $_POST[pos19];
    $pos20 = $_POST[pos20];
    $pos21 = $_POST[pos21];
    $pos22 = $_POST[pos22];
    $pos23 = $_POST[pos23];
    $pos24 = $_POST[pos24];
</code></pre>
