This works ok if # is in the channel name that the person tries to join. But if # isn't, , I get the error " test No such channel "

Most servers and IRDs that I know of usualy dont alow a channel name without the # symbol

To answer your question, #$! should be changed to $chr(35) $+ $!

But since there's a much simpler way, save yourself some headache by only using: join #$$?="channel?"

Try using this as a code now you can repeat the code to
add as many channels as you want to use in your Auto-Join

Code:

  
if ($did == 2) { 
  if (%jchan1 == $null) { set %jchan1 $?="Enter the #Channel you wish to join:") }
  if (%jchan1 != $null) { /join %jchan1 }
  else { halt }
}

I found it alot easer to add the channels I want into Mirc Options\Connect\perform that way I could specify the network I wanted the ajuto join to join the channels in.
other wise you might join another network and still join the same channels

Yeah, this also supports another channel symbols as well, such as "&channel" (won't be converted to #&channel") and the like, I'd guess it checks $chantypes or something.

I guess what would be really great if Mirc would let us add channels to the Perform like we would add a nick to the auto op or the notify part of mirc

Open the "Favorites" (3rd icon from left on toolbar), click "Add", add the #channel and the network and check "autojoin on connect" - voila!