一段asp转php

<%if request.QueryString("start") <>"" then%>
<%if cint(start)>0 then%>
<a href="search.asp?q= <%=q%>&start= <%if request.QueryString("start") <>"" and cint(start)>0 then%> <%=start-cint(num)%> <%end if%>&num= <%if num <>"" then%> <%=num%> <%else%>20 <%end if%>" target="_top">上一页 </a>
<%end if%>
<%end if%>
&nbsp; <a href="search.asp?q= <%=q%>&start= <%if request.QueryString("start") <>"" then%> <%=start+cint(num)%> <%else%> <%=start%> <%end if%>&num= <%if num <>"" then%> <%=num%> <%else%>20 <%end if%>" target="_top">下一页 </a>
</center>

---

PHP code:

<?php
$start = $_GET["start"];
if($start != ""){
if((int)$start>0){
?>
<a href="search.asp?q=<?php echo $q?>&start=<?php echo (int)$start-(int)$num?>&num=<?php if($num !="") echo $num; else echo 20;?>" target="_top">上一页 </a>
<?php
}
}
?>
&nbsp;<a href="search.asp?q=<?php echo $q?>&st