This is not correct:
if (answer == ("n") || ("N"))
It should be
if (answer == "n" || answer == "N")
It is instructive to find out why your current code compiles though: in C++ and in C, an implicit != 0
is added to conditions that do not represent a Boolean expression. Therefore, the second part of your expression becomes
"N" != 0
which is always true
: "N"
is a string literal, which can never be NULL
.