add something to a vector c++ code example

Example 1: Appending a vector to a vector in C++

Input:
    vector<int> v1{ 10, 20, 30, 40, 50 };
    vector<int> v2{ 100, 200, 300, 400 };

    //appending elements of vector v2 to vector v1
    v1.insert(v1.end(), v2.begin(), v2.end());

    Output:
    v1: 10 20 30 40 50 100 200 300 400
    v2: 100 200 300 400

Example 2: Insert into vector C++

// inserting into a vector
#include <iostream>
#include <vector>

int main ()
{
  std::vector<int> myvector (3,100);
  std::vector<int>::iterator it;

  it = myvector.begin();
  it = myvector.insert ( it , 200 );

  myvector.insert (it,2,300);

  // "it" no longer valid, get a new one:
  it = myvector.begin();

  std::vector<int> anothervector (2,400);
  myvector.insert (it+2,anothervector.begin(),anothervector.end());

  int myarray [] = { 501,502,503 };
  myvector.insert (myvector.begin(), myarray, myarray+3);

  std::cout << "myvector contains:";
  for (it=myvector.begin(); it<myvector.end(); it++)
    std::cout << ' ' << *it;
  std::cout << '\n';

  return 0;
}