This is the first clue you have given that you are running Windows machines.

IF these machines are on the same domain, and/or IF your login credentials on C have access to the shares on A and B, you can do something like this from the command-line on machine C:

C:\> perl  \\A\Path\to\code\share\codefilename.pl \\B\path\to\data\Dat
+afile.fil
[download]

Then your prograam can use the diamond operator to access the file, without being programmed explicitly for file access on a remote machine.

If the machines do not have explicit shares, and if you have administrator priviledges,
You can access the "hidden" shares at the root of the drive like:

  \\A\C$\path\to\data-or-code
[download]

Note : C$ indicates the C:\ drive.