计算变量内容有多少个句子。 每个句子必须以点号、问号或者感叹号结尾。(.?!)
Example 5.6. count_sentences
<?php
$smarty->assign('articleTitle',
'Two Soviet Ships Collide - One Dies.
Enraged Cow Injures Farmer with Axe.'
);
?>
模板是：
{$articleTitle}
{$articleTitle|count_sentences}
输出：
Two Soviet Ships Collide - One Dies. Enraged Cow Injures Farmer with Axe. 2