本文实例讲述了php函数实现从一个文本字符串中提取关键字的方法。分享给大家供大家参考。具体分析如下：
这是一个函数定位接收一个字符串作为参数（连同其他配置可选参数），并且定位该字符串中的所有关键字（出现最多的词），，返回一个数组或一个字符串由逗号分隔的关键字。功能正常工作，但我正在改进，因此，感兴趣的朋友可以提出改进意见。
/** * finds all of the keywords (words that appear most) on param $str * and return them in order of most occurrences to less occurrences. * @param string $str the string to search for the keywords. * @param int $minwordlen[optional] the minimun length (number of chars) of a word to be considered a keyword. * @param int $minwordoccurrences[optional] the minimun number of times a word has to appear * on param $str to be considered a keyword. * @param boolean $asarray[optional] specifies if the function returns a string with the * keywords separated by a comma ($asarray = false) or a keywords array ($asarray = true). * @return mixed a string with keywords separated with commas if param $asarray is true, * an array with the keywords otherwise. */function extract_keywords($str, $minwordlen = 3, $minwordoccurrences = 2, $asarray = false){ function keyword_count_sort($first, $sec) {return $sec[1] - $first[1]; } $str = preg_replace('/[^\\w0-9 ]/', ' ', $str); $str = trim(preg_replace('/\s+/', ' ', $str)); $words = explode(' ', $str); $keywords = array(); while(($c_word = array_shift($words)) !== null) {if(strlen($c_word)
希望本文所述对大家的php程序设计有所帮助。