关于一个截字符串的代码？？
<%
'*************************************************
'函数名：gotTopic
'作 用：截字符串，汉字一个算两个字符，英文算一个字符
'参 数：str ----原字符串
' strlen ----截取长度
'返回值：截取后的字符串
'*************************************************
function gotTopic(str,strlen)
if str="" then
gotTopic=""
exit function
end if
dim l,t,c, i
str=replace(replace(replace(replace(str," "," "),""",chr(34)),">",">"),"<","<")
l=len(str)
t=0
for i=1 to l
c=Abs(Asc(Mid(str,i,1)))
if c>255 then
t=t+2
else
t=t+1
end if
if t>=strlen then
gotTopic=left(str,i) & "…"
exit for
else
gotTopic=str
end if
next
gotTopic=replace(replace(replace(replace(gotTopic," "," "),chr(34),"""),">",">"),"<","<")
end function
在很多整站程序里头，都有看到段代码，红色的那部分谁能帮忙解释下什么意思，还有就是这段代码用来干什么的，什么情况下能用的找？？？
