PHP Country Codes?

I'm trying to redirect users based on their county. I found some code that should work out, but I'm not sure how I can find out each countries code. As you can see in the code below different countries use 'AF' and 'BY' etc... Is there a list of the country codes? I'm not worried if users get passed it. The code is for advertising purposes. Thanks

if($TLCC == 'AF'
  || $TLCC == 'BY'
  || $TLCC == 'VE'
  || $TLCC == 'VN')
{
    header('Location: http://www.examplesite.com');
}

PHP:

 

Here you can find this list. http:// xml.coverpages.org/country3166.html

 

http:// xml.coverpages.org/country3166.html

 

Thanks a ton!