How does ASP get the address of the first image in the code

'把pattern 又修改了下
'code要检测的代码
'http://www.downcodes.com/asp.asp
'leixing html 或者ubb
'nopic 代码没有图片时默认值
function toppic(code,leixing,nopic)
        set regex = new regexp
        regex.ignorecase = true
        regex.global = true
        if leixing = "html" then
                regex.pattern = "<img(.*?)srcs?=s?(u0022?)([^u0022/>]+)"
        else
                regex.pattern = "[img]([^u005B]+)“
        end if
        set matches = regex.execute(code)
        if regex.test(code) then
                                  if leixing = "html" then
                           toppic = matches(0).submatches(3)
                                  else
                                           toppic = matches(0).submatches(0)
                                  end if
        else
                toppic = nopic
        end if
end function
code1 = "<img src=""1.gif"">"
pic = toppic(code1,"html","nopic.gif")
response.Write pic