求一正则
<Results>
        <id>673</id>
        <dfdfsdfsdfs>2</dfdfsdfsdfs>
        <sadasdsadsadsad>1067</sadasdsadsadsad>
    </Results>
把<Results></Results>
里面的<xxxxxx>YYYYYYY</xxxxxx>全部
YYYYYY转换成123 
------解决方案--------------------
echo preg_replace('/([^<]+)>[^<]+<\/\1/s','$1>123</$1',$s);