<?php
$text = "123456789";
//保存一段文字
echo substr($text,strripos($text,"5")+1);
//输出5之后内容
echo substr($text,0,strrpos($text,"5"));
//输出5之前内容
echo substr(substr($text,0,strrpos($text,"8")),strripos(substr($text,0,strrpos($text,"8")),"5")+1);
//输出5之后8之前的内容
?>


<?php
preg_match('/.*?<p>(\d*?)<\/p>.*?/', "<p>blog.gumengya.com</p>", $res);
echo $res;
//输出 blog.gumengya.com
?>