如何获得向量的结尾并将其分配给字符串

Question

I want to get the last element of the vector and then assign it to a string but I seem to have problems.

Imagine this vector has already been filled but I do not know how much so I tried to do this.

std::vector<std::string> vec;
std::string s = vec.end();

Would a loop work and then just get the last index ?

This did not work so is there a way to get the end of a vector?

EDIT------

out.push_back(r.validateR(str));
appendCustomizedOutput = out.back();
DCS_LOG_DEBUG("END " << appendCustomizedOutput);
split(test,appendCustomizedOutput,boost::is_any_of("\n"));
DCS_LOG_DEBUG("END " << test[0]);

When i try to print test[0] nothing is printed and i do not know why ?

Answer 1

vector::end() returns an iterator that is one beyond the last real element in the vector (it's used primarily for checking while iterating).

Best way would be:

std::string s = vec.back(); // last item

As @JamesKanze and @PeterWood says, don't forget to check for empty vector - else it's undefined behaviour...

Answer 2

That's what vec.back() is for. Just make sure that the vector isn't empty first.

Answer 3

Use vec.back() to get a reference to the last element. Use vec.pop_back() to remove the last element (without returning it).

Answer 4

container.end() (or whatever kind of container) will return an iterator to the end of the container. To get the last item in the container, you want container.back() instead:

std::string s = vec.back();

Answer 5

end() returns an iterator referring to the past-the-end element in the vector container. You need back() : it returns a reference to the last element in the vector container.