Vector 

Vector is a quite useful sequence container, and it works exactly as an array, except that the vector can grow and shrink at runtime while an array is of a fixed size. However, the data structure used under the hood in an array and vector is a plain simple built-in C/C++ style array.  

Let's look at the following example to understand vectors better:

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main () {
  vector<int> v = { 1, 5, 2, 4, 3 };

  cout << "\nSize of vector is " << v.size() << endl;

  auto pos = v.begin();

  cout << "\nPrint vector elements before sorting" << endl;
  while ( pos != v.end() )
    cout << *pos++ << "\t";
  cout << endl;

  sort( v.begin(), v.end() );

  pos = v.begin();

  cout << "\nPrint vector elements after sorting" << endl;

  while ( pos != v.end() )
    cout << *pos++ << "\t";
  cout << endl;

  return 0;
}

The preceding code can be compiled and the output can be viewed with the following commands:

g++ main.cpp -std=c++17
./a.out

The output of the program is as follows:

Size of vector is 5

Print vector elements before sorting
1     5     2     4     3

Print vector elements after sorting
1     2     3     4     5