Checks if file is UTF-8 and without BOM

checkUTF8BOM.php

/*
Thanks to
http://www.php.net/manual/en/function.mb-detect-encoding.php#91051
http://stackoverflow.com/questions/8907196/check-if-csv-file-is-in-utf-8-with-php
*/

if (! mb_check_encoding($data, 'UTF-8')) {
	exit("Not UTF-8");
}
else
{
	define ('UTF8_BOM' , chr(0xEF) . chr(0xBB) . chr(0xBF));
	$first3 = substr($data, 0, 3);
	if ($first3 == UTF8_BOM)
	{
		exit("UTF-8 with BOM");
	}
	else
	{
		exit("UTF-8 without BOM");
	}
}

hi, i want save the file without bom how can i do?

$data = substr($data, 3);
:))