Need help understanding SUBSTITUTE MID SUBSTITUTE REPT formula

[szakharov7723]

So yeah surprisingly I didn't find any explanations on this semi complicated formula
=SUBSTITUTE(MID(SUBSTITUTE("_" & B7&REPT(" ",6),"_",REPT(",",255)),2*255,255),",","")

So here I used it to extract a value between "_" characters. But I want to make other additions/operations to this formula and in order to do that I need to understand every part of it.
I tried to take it apart, but it is not that obvious, because it shows no real value, so I can't really locate where operation takes place.

Can you please help me understand this formula in specifics ?
Like why exactly each formula has been used and what are these numbers and symbols.

 

[jtakw]

Hi,

It's probably better if we start with you showing a list of your possible data, and what you need extracted from it, then go from there.

 

[szakharov7723]

Hi,
The idea was using this formula make a change in file path, so it goes not to 1 January, but to 2 January file, and so on.
However I actually found a potentially better way of doing it by concatenating different elements of file path using respective date. And applying Evaluate VBA code.
Thank you for responding though

 

[jtakw]

You're welcome, glad you sorted it out.