Sharing long urls by email or on social media sites is never a good idea, this is why most people are using urls shorteners such as biy.ly or Tinyurl. This function takes a single parameter, an url, and will return a short url using the Tinyurl service.

function getTinyUrl($url) {
    return file_get_contents("http://tinyurl.com/api-create.php?url=".$url);
}

Usage

Nothing complicated, simply pass an url to the function to get its short url:

$my_url = getTinyUrl('http://www.phpsnippets.info/test-existence-of-a-given-url-with-curl');
echo 'Short url: '.$my_url;

If you want to use this snippet within WordPress, you can do so by using the following within the loop:

getTinyUrl(get_permalink($post->ID));