C++ factorial

Question

Problem = I understand how it works but I don't understand how it's written because the product is not stored in any variable. We have to take for granted that the product is stored in the function an it really doesn't rime with logic to me.

Answer 1

OMG... I just understood it. The variable stores it's new value of (-1) for the next run... Ok thanks people... Nevermind... Swiping left.