iterator demo

#include <iostream>#include <vector>using namespace std;template <typename T>void display_vector(const vector<T> &vec);int main(){    vector<int> ivec;    for (int i = 0; i < 10; ++i)        ivec.push_back(i);    display_vector(ivec);    for (auto it = ivec.begin(); it != ivec.end(); ++it)        *it *= 2;    display_vector(ivec);    return 0;}template <typename T>void display_vector(const vector<T> &vec){    for (auto elem : vec)        cout << elem << " ";    cout << endl;}