How do I create a new list from an existing list using the first n-5 elements?

Question

How do I create a new std :: list from an existing std :: list, taking the first n-5 elements? n - size of the existing list (list)

+3

PaolaJ. 06 Feb 13 at 18:12

1 answer

Steve jessop · Accepted Answer · 2013-02-06T18:15:08+0000

std::list<T> newlist(oldlist.begin(), std::prev(oldlist.end(), 5));

where T

is the value type of the old list.

std::prev

is new in C ++ 11, but if you don't have it, you can use std::advance

instead:

std::list<T>::const_iterator end = oldlist.end();
std::advance(end, -5);
std::list<T> newlist(oldlist.begin(), end);

In any case, it is your responsibility to provide oldlist.size() >= 5

. Neither std::prev

, nor std::advance

does it for you.