ASP截取文章一部分显示（无损HTML）

<%
Function LeftH(str,l)
dim labelt,labels
dim ishtml
ishtml=false
dim res
dim c,c2
dim n
n=0
dim maxlen
maxlen=len(str)
dim i
i=0
dim b,e
do while n<l and i<maxlen
  i=i+1
  c=mid(str,i,1)
  if c="<" then
   c2=mid(str,i+1,1)
   ishtml=true
   b=i
  end if
  res=res+c
  if ishtml=false then
   n=n+1
  else
   if c=">" then
    if ishtml=true and c2<>"/" then
     labels=mid(str,b+1,i-b)
     e=InStr(labels," ")
     if e>0 then
      labels="</"+left(labels,e-1)+">"
     else
      labels="</"+labels
     end if
     labelt=labels+labelt
    end if
    ishtml=false
   end if
  end if
loop
leftH=res+labelt
end function

dim str
str="<b><font color=red size=4 face=黑体>中华人</font>民共和国</b>"
response.write "原始的效果：<br><br>"+str
response.write "<script>alert('原始的html代码："+str+"');</script>"
response.write "<hr>"
str=lefth(str,4)
response.write "截取后的效果：<br><br>"+str
response.write "<script>alert('截取后的html代码："+str+"');</script>"
%>