Answer 1

This app is good but sometimes it feels annoying

I use void main() without any return type rather using int main() with return type. You can try using void main. It works just fine

Also using namespace std .. i don't know what is the use of this line(i know ... but just saying :p). I mean i have done filehandling without this and done classes and OPP programing
You can refer to books but don't get confused. Codes changes from books to books. Just take up one style of coding and it will work just fine

Also it depends on the different IDE you use