Question

I have two vectors

typedef std::vector<std::string> messages;
typedef std::vector<std::string> addMessage;
messages st;
addMessage additionlMsgs;

when the user inputs a string i then split that string by a certain character which is then splitted into st

i want to copy that vector over to additionalMsgs at some point but i get a run time error i cannot see why.

i try to copy it over as follows

 copy(st.begin(), st.end(), additionlMsgs.begin());

can you see anything that is incorrect?

Thanks
Shamari

Answer 1

It sounds like you’re looking for std::back_inserter:

std::copy(st.begin(), st.end(), std::back_inserter(additionlMsgs));

That’ll append to additionlMsgs. If you wish to overwrite its contents, you might want to use:

additionlMsgs = st;

The code you have right now never adds new elements to additionlMsgs; it simply overwrites existing ones without performing any bounds checking. If additionlMsgs is too short, you get undefined behaviour.