Thursday, 02 November, 2000

File Splitter Tool

I went searching the other night for a program that will split a large file into smaller chunks so that it can be downloaded in pieces and reconstructed.  I don't need this type of program very often these days, what with my cable modem, ZIP drive, and CD-R/CD-RW.  Trafficking in 20 megabyte files today is a whole lot easier than 1 megabyte files were 10 years ago.  But 9 gigabyte files are still a problem.

My first stop was WinFiles.com, where I searched for "file split" and came up with this page of hits.  I can't say that I looked at all of them, but the half dozen I looked at couldn't handle splitting a 9 gigabyte file into gigabyte-sized chunks.  Most failed when they tried to read the file size, because 9 gigabytes overflows a long integer (2 gigabytes signed, or 4 gigabytes unsigned).  Others failed because they tried to allocate a 1 gigabyte file I/O buffer and overflowed my virtual memory.

If you want something done right...

Today I completed my Splitter program, which should  work for any file up to 9,223,372,036,854,775,808 bytes in size.  Of course, I don't have a file that large with which to test the program, but I did split a 5-gigabyte file into 1-gigabyte chunks.  The program lets you specify the chunk size and the output directory, and even creates a batch file that will reconstruct the file from the pieces.

The program isn't terribly fancy, but it gets the job done.  I wrote it more for the exercise than anything else.  As with other Delphi projects, it was a pleasure to have the UI code essentially written so that I could concentrate on the actual processing.  You can get the Delphi source here.