Function of vector

//max_size() – Returns the maximum number of elements that the vector can hold.
//capacity() – Returns the size of the storage space currently allocated to the vector expressed as number of elements.
//resize(n) – Resizes the container so that it contains ‘n’ elements.
//shrink_to_fit() – Reduces the capacity of the container to fit its size and destroys all elements beyond the capacity.
//front() – Returns a reference to the first element in the vector
//back() – Returns a reference to the last element in the vector

// C++ program to illustrate the
// capacity function in vector
#include <iostream>
#include <vector>
  
using namespace std;
  
int main()
{
    vector<int> g1;
  
    for (int i = 1; i <= 5; i++)
        g1.push_back(i);
 
    cout << "\nCapacity : " << g1.capacity();
    cout << "\nMax_Size : " << g1.max_size();
  
    // resizes the vector size to 4
    g1.resize(4);
  
    // prints the vector size after resize()
    cout << "\nSize : " << g1.size();
  
    // Shrinks the vector
    g1.shrink_to_fit();
    cout << "\nVector elements are: ";
    for (auto it = g1.begin(); it != g1.end(); it++)
        cout << *it << " ";
  
         cout << g1.front();
        
         cout << g1.back();
    return 0;
}

Output:
Capacity : 8
Max_Size : 4611686018427387903
Size : 4
Vector elements are: 1 2 3 4
front:1
back:4