Quick replacement to PHP's date() function to handle the 'u' format specifier (for microseconds)

date_with_micro.php

<?php
/**
 * Quick replacement to date() function to handle the 'u' format specifier (for microseconds)
 * @param string $format Date format string - the same format string you would pass to date() function
 * @param float $timestamp [optional] Unix timestamp with microseconds - Typically output of <b>microtime(true)</b>
 * @return string Formatted string
 */
function date_with_micro($format, $timestamp = null) {
  if (is_null($timestamp) || $timestamp === false) {
		$timestamp = microtime(true);
	}
	$timestamp_int = (int) floor($timestamp);
	$microseconds = (int) round(($timestamp - floor($timestamp)) * 1000000.0, 0);
	$format_with_micro = str_replace("u", $microseconds, $format);
	return date($format_with_micro, $timestamp_int);
}