This simple and inefficient tool was made to rename files in a folder that were numbered incorrectly. The files had the correct number in their name, but since most OSes use alphabetical order, it was not like this:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10...

but like this:

1, 10, 11, 12-19, 100, 101, 102... 2, 20, 21-29, 200, 201, 202...

This is easily fixed by adding zeros before the actual number, up to the number of needed digits:

001, 002, 003, 004... 010, 011... 020, 021... 100, 101...

The code only supports up to 3 digits but can easily be updated to handle more.