It's not entirely clear from your question, but if b
and data
are both std::vector<int>
, then you can do five related things:
Initializing a new data
with b
std::vector<int> data = b; // copy constructor
Initializing a new data
with b
std::vector<int> data(begin(b), begin(b) + n); // range constructor
Copying b
entirely into an existing data
(overwriting the current data
values)
data = b; // assignment
Copying the first n
elements of b
into an existing data
(overwriting the current data
values)
data.assign(begin(b), begin(b) + n); // range assignment
Appending the first n
elements of b
onto an existing data
data.insert(end(a), begin(b), begin(b) + n); // range insertion
You can also use end(b)
instead of begin(b) + n
if b
has exactly n
elements. If b
is a C-style array, you can do a using std::begin;
and using std::end
, and the range construction/assignment/insertion will continue to work.