PHP统计字符串中单词出现次数的函数

<?
/**
* 统计字符串里单词出现次数
* edit: www.jbxue.com
*/
function full_count_words($str) {
    //返回完整数组，包含字符串里每个单词

    $words = str_word_count($str,1);
    $result = array();
    foreach ($words as $w) {
        $lw = strtolower($w);
        //判断单词是否是第一次出现，是则设置为1，否则就增加1

        if (!(isset($result[$lw]))) {
            $result[$lw] = 1;
        } else {
            $result[$lw]++;
        }
    }
    return $result;
}
?>

<?
$test = "Good luck to you,good by! me to ,good ,good";
$wordcount = full_count_words($test);
//echo $wordcount['good'];

print_r($wordcount);
?>