Your question is poorly formulated. Try again. It looks like you want the gaps too, in separate files.

Also, your description of the desired output is inconsistent. Why is

File-arr2-3.txt
---
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if you don't have an empty slot in the 2d array?

Also, file File-arr1-8.txt seems to be missing - if both arrays are aligned. Then it should contain

arr1[9],arr1[10]
[download]

Hint: to write to files, you have to open them, then print to them, close them.
Can't say more about that.