Functions to transform dates & times in php

/**
 * functionsDateTime.php :  transformation of date & time fields.
 */
 
 
/**
 * Returns name of day of a date informed.
 *
 * @param string $fromData (yyyy-mm-dd)
 * @param array $arrDayName (0 = Sunday, 1 = Monday, 2 = Tuesday, 3 = Wednesday, 4 = Thursday, 5 = Friday, 6 = Saturday, 7 = Sunday)
 * @return string
 */
function weekdayname ($fromData, $arrDayName)
{
	$intTimeStamp = mktime(0, 0, 0, substr($fromData, 5, 2), substr($fromData, 8, 2), substr($fromData, 0, 4));
	$weekDay = date('w', $intTimeStamp);
    return $arrDayName[$weekDay];
}
 
 
/**
 * Return name of month of a date informed.
 *
 * @param string $fromData (yyyy-mm-dd)
 * @param array $arrMonthName  (0 = January, 1 = February 2 = March 3 = April, 4 = May, 5 = June, 6 = July, 7 = August, 8 = September, 9 = October, 10 = November, 11 = December)
 * @return string
 */
function monthname ($fromData, $arrMonthName)
{
	$intTimeStamp = mktime(0, 0, 0, substr($fromData, 5, 2), substr($fromData, 8, 2), substr($fromData, 0, 4));
	$intMonth = date('m', $intTimeStamp);
    return $arrMonthName[$intMonth - 1];
}
 
/**
 * Transform a date depending format informed.
 *
 * @param string $fromData
 * @param string $strFormat
 * Possible formats are: 'YYYYMMDD_DDMMYYYY','YYYYMMDD_DDMMYY','DDMMYYYY_YYYYMMDD'
 * @return string
 */
function transformdate($fromData, $strFormat ='DDMMYYYY_YYYYMMDD')
{
	$newDate = '';
	switch ($strFormat){
		case 'YYYYMMDD_DDMMYYYY':
			$newDate = substr($fromData, 8, 2).substr($fromData, 4, 4).substr($fromData, 0, 4).substr($fromData, 10);
		break;
		case 'YYYYMMDD_DDMMYY':
			$newDate = substr($fromData, 9, 2).substr($fromData, 6, 2).substr($fromData, 3, 2);
		break;	
		case 'DDMMYYYY_YYYYMMDD':
			$newDate = substr($fromData, 6, 4).substr($fromData, 2, 4).substr($fromData, 0, 2).substr($fromData, 10);
		break;		
	}
    return $newDate;
}
 
 
function transformtime($time){
 
if ($time == '') return '00:00:00';
if ($time == '00:00:00') return '00:00:00';
 
$pattern="/^([0-1][0-9]|[2][0-3])[\:]([0-5][0-9])[\:]([0-5][0-9])$/";
if(preg_match($pattern,$time))
     return $time;
return '00:00:00';
 
}
 
 
/**
 * Return end date of informed date. 
 *
 * @param string $fromData
 * @return string
 */
function lastmonthday($fromData)
{
	$newDate = '';
	$intTimeStamp = mktime(0, 0, 0, substr($fromData, 5, 2), substr($fromData, 8, 2), substr($fromData, 0, 4));
	$numDays = intval(date("t",$intTimeStamp));	
	$newDate = substr($fromData, 0, 4).substr($fromData, 4, 4).$numDays;
	return $newDate;
}
 
 
/**
 * Return starting date of informed day. 
 *
 * @param string $fromData
 * @return string
 */
function startingmonthday($fromData)
{
	$newDate = '';
	$newDate = substr($fromData, 0, 4).substr($fromData, 4, 4).'1';
	return $newDate;
}