vectors in C++

#include <iostream>
#include <vector>

//     at, back() ,    begin() ,   size, clear(), 
using namespace std;

int main() {
  // Create a vector of integers
  vector<int> numbers = {10, 20, 30, 40};

  // Access element using at() for safe access with bounds checking
 
    int second_element = numbers.at(1); 

    int x = numbers[1]; // Access the element at index 1 (20)
    cout << "Second element: " << second_element << endl;
    cout<<x<<endl;
    int z = numbers.back();
    cout<<z<<endl;

    vector<int> ::iterator iter = numbers.begin();

    // numbers.clear();
    // cout<<numbers.at(2);
    // cout<<numbers.size();
    
   
    // cout<<numbers.empty();  // true
    // numbers.erase(numbers.begin() + 1); // always work with .begin() or .end() function
    // cout<<numbers.size();

    cout<<"usign at " <<numbers.at(0)<<endl;
    cout<<"using front"<<numbers.front()<<endl;
   
    cout<<numbers.at(0)<<endl;
    
  numbers.pop_back();
  cout<<numbers.size()<<endl;
  numbers.push_back(90);
  cout<<numbers.at(3)<<endl;
  cout<<numbers.size()<<endl;
  numbers.resize(6);
  cout<<numbers.size();

    // Example of potential out-of-bounds access (handled by the try-catch block)
    // int out_of_bounds = numbers.at(10);  // This would throw an exception
  

  return 0;
}