How do I write the following explanation in excel formula?

Question

Suppose I am working on A1, B1 and the formula is being written in C1:

If A1 is equal to B1 then C1 is 4 else -1, if A1 is blank then C1 is 0

( Where, B1 can never be empty )
I am able to write the formula for the first logic but unable to merge with second, and as I am working on 75 such columns so I wanted to generalize it...

Answer 1

Excel appears to support nested if functions.

https://www.techonthenet.com/excel/formulas/if_nested.php

You can then combine this with the check for blank.

https://exceljet.net/formula/if-cell-is-blank

I imagine the formula for C1 would look something like this:

IF(A1=B1, 4, IF(A1="", 0, -1))

on the assumption that assigning 0 to A1 on blank takes precedence over assigning -1 on A1 not equals to B1.
I don't have Excel with me at the moment so I can't try this. Sorry if I made any mistakes.

Answer 2

Maybe VBA is to apply