PHP study notes: Enter a sentence and output the words in reverse order

<?php<br />/**<br /> * Created by PhpStorm.<br /> * User: Administrator<br /> * Date: 2016/9/25 0025<br /> * Time: 22:29<br /> */<br />//需要被倒序的字符串<br />$str="I am a handsome boy.";<br />$str_len=strlen($str);<br />//echo $str_len;输出结果为20，确认没问题。<br />//截取.号之前的字符substr(string,start,length)<br />$str=substr($str,0,$str_len-1);<br />//echo $str;得出I am a handsome boy，语句没问题<br />//转为数组<br />$str_arr=explode(' ',$str);<br />//var_dump($str_arr);结果无误<br />//倒序接收<br />$str_str_new=array_reverse($str_arr);<br />//数组转为字符串<br />$str_str_new_str=implode(' ',$str_str_new);<br />echo '转换前：'.$str."<br/>".'转换后：'.$str_str_new_str.'.';