function UBBCode(strContent)
if strAllowHTML <> 1 then
strContent = HTMLEncode(strContent)
else
strContent = HTMLcode(strContent)
end if
dim re
Set re=new RegExp
re.IgnoreCase =true
re.Global=True

if strIMGInPosts = "" then
re.Pattern="(\[IMG\])(.[^\[]*)(\[\/IMG\])"
strContent=re.Replace(strContent,"screen.width-333)this.width=screen.width-333"">")
end if

end function

strContent=re.Replace(strContent，...）怎么理解，如果用php怎么实现？