From your thread title, I'm guessing that you just wrote n + 1; or similar.
This does add 1 to n, and tests to see if the result is non-zero, but doesn't assign the incremented value back to n, and throws away the result of the test.
n = n + 1;
n++; //post-increment
++n; //pre-increment
n += 1;
all increment n, but be careful how you use the post- and prefix versions.