Question

I am writing a Windows service which poll on a specific folder.
The directory contains various files, and each file derives from a previous split operation:

Input folder:

• FILE_A_PART_1_OF_2.txt
• FILE_A_PART_2_OF_2.txt
• FILE_B_PART_1_OF_3.txt
• FILE_B_PART_2_OF_3.txt
• FILE_C_PART_2_OF_3.txt
• FILE_C_PART_3_OF_3.txt
• FILE_D_PART_1_OF_3.txt
• FILE_D_PART_3_OF_3.txt
• FILE_E_PART_1_OF_1.txt

The Services should be able to merge only the complete files:

Output Folder (after the merge operation):

• FILE_A.txt
• FILE_E.txt

Input Folder (after the merge operation)

• FILE_B_PART_1_OF_3.txt
• FILE_B_PART_2_OF_3.txt
• FILE_C_PART_2_OF_3.txt
• FILE_C_PART_3_OF_3.txt
• FILE_D_PART_1_OF_3.txt
• FILE_D_PART_3_OF_3.txt

Unfortunately i have to use framework 2.0. Language is C#. I know it’s not a complicated algorithm but somehow i can’t put myself into the right direction.
The merge operation is not important, so it can be expressed like:

Merge(string[] filesPart) or Merge(List<string> filesPart).

Thank you in advance.

Answer 1

First, grab all files, with Directory.GetFiles()

And then your main tool would be the Dictionary<> class.
I think I would use something like:

class BaseFile
{   
   public int Total { ... }     
   public List<string> Parts { ... }
}    

List<string, BaseFile> baseFiles = ...;

This would allow you to scan the list of files, parse the name and store it.
After the scan, only process a file when Total == Parts.Count.

As long as the n in PART_n_OF_m remains < 10 you can simply sort the List<string> Parts.
When it can become >= 10 you’ll need something like SortedList<int, string> Parts