vector push into another vector c++ code example

Example 1: appending a vector in vector

a.insert(a.end(), b.begin(), b.end());

Example 2: how to append to a vector c++

//vector.push_back is the function. For example, if we want to add
//3 to a vector, it is just vector.push_back(3)
vector <int> vi;
vi.push_back(1); //[1]
vi.push_back(2); //[1,2]