username

Check for correctly formatted array of this type: array( array('name'=>'War and Peace', 'year'=>1865), array('name'=>'Different Seasons', 'year'=>1982), )

Check for correctly formatted array of this type: array('a', 'bb', 'ccccc',)

Check for correctly formatted array of this type: array(1,2,3,)

Easly to check tel:// or sms:// protocols.

Zero length negative lookbehind

http://bitsnoop.com/trackers/ has a list of active trackers quick dirty regex to extract only the tracker names in order to paste said tracker names to utorrent/deluge

Use part 1, 3 , 5 for establish the portable callsign like 1 = DL/ 2 = F5UII 3 = /QRP

reference pattern checking

Get information from File URL such as, Extension. Parent folder name. Drive name. File name.