PHP - get first two sentences of a text?

Question

My variable $content contains my text. I want to create an excerpt from $content and display the first sentence and if the sentence is shorter than 15

Answer 1

This would make sure it never returned a half-word;

$short = substr($content, 0, 100);
$short = explode(' ', $short);
array_pop($short);
$short = implode(' ', $short);
print $short;