Blank Cell

I am having trouble understanding your request.
to put it in a narrative form, your formula says that, first if C5 is blank, leave the target cell blank, otherwise, second if both C2 and C5 equal "C" to make the target cell C1, lastly if C5 equals C2, return 1, otherwise return 0.
so

How can I modify this formula in order to show a blank cell instead 0 before the formula get performed.

what part are you asking this about, the last part -- which is the only part with a 0? or what does before the formula get performed mean?

could you clarify or post a small sample with formula AND desired result? instructions for uploading a workbook are at the top of the post in the yellow banner.