how to compare current and previous element in list

Question

Hi

Refer code below:

map<string, vector<string>> data; has vector as value. If I need list as value, how to iterate over list? We can iterate with begin and end, but how to compare last element with current element for list?

https://www.sololearn.com/compiler-playground/cn5CwUsYlr6Y

Answer 1

Have you tried using std::prev () ?

https://en.cppreference.com/w/cpp/iterator/prev

https://code.sololearn.com/c4566RUf3hUn/?ref=app

Answer 2

Ketan Lalcheta "std::advance ()" doesn't return anything, it simple advances the iterator passed to it.

Answer 3

I was trying advance with -1.. is it correct ? I was getting incomplete type error with below :

auto pv = std::advance(it,-1);