php按照单词截取子串

转自：http://hi.baidu.com/hiosiao/blog/item/f90e7fe7363ff128b83820b3.html

function subwords($words,$num){//从 $words 字符串中 截取前 $num 个单词// functioned by PHP designer Hiosiao,                $total_num = str_word_count($words); // 获取$words 中单词个数if($total_num <= $num){   // 如果$words 中单词个数少于 $numreturn $words;}else{$pattern = '/([\S]+?[ ]+){'.$num.'}/';preg_match($pattern, $words, $out);return $out[0].'...'; //如果字符串过长，将以 ... 结束}}