二级域名
利用上面的代码可以用二级域名的形式来访问http://www.域名1/文件夹/中对应的文件夹内的网页，比如二级域名为：http://520.域名1.com，经过上面的代码就可以直接访问http://www.域名1.com/文件夹/520/
<font face="新宋体"><span style="COLOR: #0000bb"></span><span style="COLOR: #0000bb"> </span></font> <font face="新宋体"><span style="COLOR: #0000bb">$x</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #007700">=</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #0000bb">str_replace</span><span style="COLOR: #007700">(</span><span style="COLOR: #dd0000">'.域名1'</span><span style="COLOR: #007700">,</span><span style="COLOR: #dd0000">''</span><span style="COLOR: #007700">,</span><span style="COLOR: #0000bb">$_SERVER</span><span style="COLOR: #007700">[</span><span style="COLOR: #dd0000">'HTTP_HOST'</span><span style="COLOR: #007700">]</span><span style="COLOR: #007700">)</span><span style="COLOR: #007700">;</span><span style="COLOR: #0000bb"> </span></font> <font face="新宋体"><span style="COLOR: #007700">if</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #007700">(</span><span style="COLOR: #0000bb">$x</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #0000bb">!=</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #dd0000">"www"</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #007700">&&</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #0000bb">$x</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #0000bb">!=</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #dd0000">""</span><span style="COLOR: #007700">)</span><span style="COLOR: #0000bb"> </span><span style="COLOR: #007700">{</span><span style="COLOR: #0000bb"> </span></font> <span style="COLOR: #0000bb"><font face="新宋体">Header</font></span><font face="新宋体"><span style="COLOR: #007700">(</span><span style="COLOR: #dd0000">"Location:http://www.域名1.com/文件夹/"</span><span style="COLOR: #007700">.</span><span style="COLOR: #0000bb">$x</span><span style="COLOR: #007700">.</span><span style="COLOR: #dd0000">"/"</span><span style="COLOR: #007700">)</span><span style="COLOR: #007700">;</span><span style="COLOR: #0000bb"> </span></font> <font face="新宋体"><span style="COLOR: #007700">}</span><span style="COLOR: #007700">else</span><span style="COLOR: #007700">{</span><span style="COLOR: #0000bb"> </span></font> <span style="COLOR: #0000bb"><font face="新宋体">Header</font></span><font face="新宋体"><span style="COLOR: #007700">(</span><span style="COLOR: #dd0000">"Location:http://www.域名2.com"</span><span style="COLOR: #007700">)</span><span style="COLOR: #007700">;</span><span style="COLOR: #0000bb"> </span></font> <font face="新宋体"><span style="COLOR: #007700">}</span><span style="COLOR: #0000bb"> </span></font> <span style="COLOR: #0000bb"><font face="新宋体">?></font></span>
