swap demo

#include <iostream>#include <vector>using namespace std;template <typename T>void display_vector(const vector<T> &vec);int main(){    vector<int> ivec1, ivec2;    ivec1 = { 1, 2, 3 };    ivec2 = { 4, 5, 6 };    //ivec1.assign(ivec2.begin(), ivec2.end());    swap(ivec1, ivec2);    cout << "ivec1: " << endl;    display_vector(ivec1);    cout << "\nivec2: " << endl;    display_vector(ivec2);    return 0;}template <typename T>void display_vector(const vector<T> &vec){    for (auto val : vec)        cout << val << " ";    cout << endl;}