DateTime comparison (strings)

gistfile1.php

<?php
function calculateDateDiff($strStart, $strEnd) {
    $objStart = DateTime::createFromFormat("m/j/Y g:i:s A", $strStart);
    $objEnd = DateTime::createFromFormat("m/j/Y g:i:s A", $strEnd);

    // Return Total Seconds
    return $objEnd->getTimestamp() - $objStart->getTimestamp();

    // Return formatted diference (7hrs 5mins and 43 seconds)
    return $objStart->diff($objEnd)->format('%hhrs %imins and %sseconds ');
}