织梦修改文章上下篇显示字数

$this->PreNext['pre']="上一篇:{$preRow['title']}";  

$preRow['title']=cn_substr($preRow['title'],30);  

$this->PreNext['next']="下一篇:{$nextRow['title']}";

$nextRow['title']=cn_substr($nextRow['title'],30);