PHP count, add colons every 2 characters

I have this string

1010081-COP-8-27-20110616214459

I need to count the last 6 characters starting from the end of this string (because it could may be long starting from the begin)

Then I need to add colons after every 2 characters.

So after counting 6 characters from the end it will be

214459

After having added the colons it wil开发者_StackOverflowl look like:

21:44:59

Can you help me achieving it?

I do not really know where to start!

Thank you

You can do this with substr, str_split and implode

The code is done on multiple lines for clarity, but can easily be done in a chain on one line:

$str = '1010081-COP-8-27-20110616214459';
//Get last 6 chars
$end = substr($str, -6);
//Split string into an array.  Each element is 2 chars
$chunks = str_split($end, 2);
//Convert array to string.  Each element separated by the given separator.
$result = implode(':', $chunks);

echo preg_replace('/^.*(\d{2})(\d{2})(\d{2})$/', '$1:$2:$3', $string);

It looks to me though like that string has a particular format which you should parse into data. Something like:

sscanf($string, '%u-%3s-%u-%u-%u', $id, $type, $num, $foo, $timestamp);
$timestamp = strtotime($timestamp);
echo date('Y-m-d H:i:s', $timestamp);

If you just want the time:

$time = rtrim(chunk_split(substr($s,-6),2,':'),':');

$final = "1010081-COP-8-27-20110616214459";

$c = substr($final, -2);
$b = substr($final, -4, 2);
$a = substr($final, -6, 2);

echo "$a:$b:$c";