CPP

how to append one vector to another c++

vector<int> a;
vector<int> b;
// Appending the integers of b to the end of a 
a.insert(a.end(), b.begin(), b.end());

assign one vector to another c++

// C++ code to demonstrate copy of vector 
// by iterative method. 
#include<iostream> 
#include<vector> 
using namespace std; 
  
int main() 
{ 
    // Initializing vector with values 
    vector<int> vect1{1, 2, 3, 4}; 
  
    // Declaring new vector 
    vector<int> vect2; 
  
    // Using assignment operator to copy one 
    // vector to other 
    vect2 = vect1; 
  
    cout << "Old vector elements are : "; 
    for (int i=0; i<vect1.size(); i++) 
        cout << vect1[i] << " "; 
    cout << endl; 
  
    cout << "New vector elements are : "; 
    for (int i=0; i<vect2.size(); i++) 
        cout << vect2[i] << " "; 
    cout<< endl; 
  
    // Changing value of vector to show that a new 
    // copy is created. 
    vect1[0] = 2; 
  
    cout << "The first element of old vector is :"; 
    cout << vect1[0] << endl; 
    cout << "The first element of new vector is :"; 
    cout << vect2[0] <<endl; 
  
    return 0; 
}

assign one vector to another c++

   // Initializing vector with values 
    vector<int> vect1{1, 2, 3, 4}; 
  
    // Declaring new vector 
    vector<int> vect2; 
  
    // Using assignment operator to copy one 
    // vector to other 
    vect2 = vect1; 

append vector to itself c++

auto old_count = xx.size();
xx.resize(2 * old_count);
std::copy_n(xx.begin(), old_count, xx.begin() + old_count);