From: Ben Giddings <bg-rubytalk@...>
Date: 2007-10-17T13:33:56+09:00
Subject: Re: Mind giving a little help?

Ok, your functions would be:

require 'uri'
require 'net/http'

# Check to see if a URL exists, returning true if it does, false if  
it doesn't
def image_exists?(url_string)

   # Create a "URI" object from the string-form URL
   url = URI.parse(url_string)

   # connect to the web server listed in the URL
   Net::HTTP.start(url.host, url.port) do |http|

     # Ask the web server for the HTTP header for something matching  
the path
     response = http.head(url.path)

     case response

     # If we get a successful response back (i.e. the server knows  
about the path)
     when Net::HTTPSuccess, Net::HTTPRedirection

       # Look at the content_type, and see if it's an image
       case response.content_type
       when "image/png", "image/gif", "image/jpeg"

         # If both of these check out, the image exists at that URL
         return true
       end
     end
   end

   # If we get to here, we have to assume the image doesn't exist
   return false
end

# Ask the user if he/she wants to save the URL
def user_wants_to_save?(url)
   # Print out the question
   print "Save #{url.chomp}? [y/N]: "

   # read in the answer
   input = $stdin.gets

   # if the answer contains a y (either upper-case or lower-case)
   if /y/i =~ input
     return true
   else
     return false
   end
end

# Open a new output file named "urls_checked.txt" and
# create a handle 'out' so we can interact with it
File.open("urls_checked.txt", "w") do |out|

   # Open the input file "urls.txt" and read it one line at a time
   # calling each line of the file 'url' as we read it
   File.foreach("urls.txt") do |url|

     # See if the URL on this line of the file exists
     if image_exists?(url)

       # If the URL exists, ask if the user wants to save it
       if user_wants_to_save?(url)

         # If so, print that URL into the output file
         out.puts url
       end
       # If the user didn't want to save the URL, do nothing
       # it won't show up in the output file
     else
       # If the URL doesn't exist, add it to the output file
       out.puts url

     end
   end
end


# Optional -- overwrite the original file with the file containing  
checked URLs
FileUtils.mv("urls_checked.txt", "urls.txt")



On Oct 16, 2007, at 22:49, Tj Superfly wrote:
> I've created 2 files with the names you have there, like you  
> suggested.
> Here are their locations. This is actually what I don't understand the
> most is this whole file thing, I think that's what throwing me off the
> most. Anyway, here are their locations:
>
> C:\Documents and Settings\nonstickglue\My Documents\TDN\urls.txt
> C:\Documents and Settings\nonstickglue\My Documents\TDN 
> \urls_checked.txt

So urls.txt is where you should put the list of all the urls you want  
to check.  Don't create urls_checked.txt, the program will create it  
and place the output there.

Take what i wrote above and see if you can figure out what's going  
on.  If you have questions post them.

Ben