翻译强力驱动I have a vector vec of structures. Such a structure has elements int a, int b, int c. I would like to assign to some int var the element c, from the last structure in a vector. Please can you provide me with this simple solution? I'm going circle in line like this:
var = vec.end().c;The immediate answer to your question as to fetching access to the last element in a vector can be accomplished using the back() member. Such as:
int var = vec.back().c;Note: If there is a possibility your vector is empty, such a call to back() causes undefined behavior. In such cases you can check your vector's empty-state prior to using back() by using the empty() member:
if (!vec.empty()) var = vec.back().c;Likely one of these two methods will be applicable for your needs.
vec.end() is an iterator which refers the after-the-end location in the vector. As such, you cannot deference it and access the member values. vec.end() iterator is always valid, even in an empty vector (in which case vec.end() == vec.begin())
If you want to access the last element of your vector use vec.back(), which returns a reference (and not iterator). Do note however that if the vector is empty, this will lead to an undefined behavior; most likely a crash.
Use back():
var = vec.back().c;var = vec.back().c; is what you want.
end() returns the iterator (not an element) past-the-end of the vector. back() returns a reference to the last element. It has a counterpart front() as well.
Try this: var = vec.back().c;
Also you may modify your code like:
var = vec.rbegin()->c;In both versions first make sure that the vector is not empty!
You can simply use back as it returns a reference to the last element.var = vec.back().c
You can use the std:vector<T>:back() function, e.g. vec.back().c. See http://www.cplusplus.com/reference/vector/vector/back/