for(j in 1:length(link$http)){
  url<-c(as.character(link$http[j]))
  filename<-paste0("result/",link$type[j],link$date[j],".txt")
  download.file(url,destfile=filename)
}

报错：Error in download.file(url, destfile = filename) :
  cannot open destfile 'result/PRS1601.txt', reason 'No such file or directory'

跪求大神指导