Question: I have a worksheet using raw data that Excel does not identify as Tables (ie. plainly putting values in adjacent cells), and on another part of my worksheet, formulas doing lookup in that data, like

```
VLOOKUP(D$1, Config!$C$4:$E$8,2,FALSE)

```

Things are going perfectly well, until I decide to declare my raw data as a table (Ctrl-T) to get some extra functionality, like auto-formatting and auto table expansion.

Once the table declared, all my formulas find #N/A in that table, whether I reference the search zone as cell reference (`Config!$C$4:$E$8`) or by its new table name (modified via the name manager).

**A clue** (I don't know what it's worth) is that the lookup key (`D$1` in my formula) and the data keys (leftmost column of `Config!$C$4:$E$8`) are numeric (values like `2015`). Excel seems to use text lookup when inside a table and fail to match `2015` (in the table) with `"2015"` (from `D$1`). This is only a clue, I may be wrong on this.

What can I do to start using tables (auto expanding is really useful) without breaking my fomulas?

**EDIT :** Things break when the lookup key (`D$1`) starts being part of a table: 2015 is now seen by formulas as "2015"

Answer: 
> 
> Sending this file with the program is required but is there any way to
>  stop a user on another from seeing the contents of this file or
>  opening the file?
> 
> 
> 

You would need to encrypt this file. You cannot use file permissions for obvious reasons, you have no control over their system, and any permissions you setup would only be valid on your system anyways.

An alternative solution is not to use a text file to store sensitive information. One simply way would be modify the data stream slightly. You could in theory perform several bit operations on various parts of the data, then when your program reads it, perform the operations to reverse them.

Another solution would be to compress the data and uncompress the data.

These solutions are only being offered since your intial ideas on how to protect the files are simply not possible.
The obvious answer here is to encrypt the file from the very start so only your program can open it. You've not mentioned what language you've written the program in so its hard to suggest a good Library.