Check out example codes for "c++ vector.back". It will help you in understanding the concepts better.

Code Example 1

// vector::back
#include <iostream>
#include <vector>

int main ()
{
  std::vector<int> myvector;

  myvector.push_back(10);

  while (myvector.back() != 0)
  {
    myvector.push_back ( myvector.back() -1 );
  }

  std::cout << "myvector contains:";
  for (unsigned i=0; i<myvector.size() ; i++)
    std::cout << ' ' << myvector[i];
  std::cout << '\n';

  return 0;
}

Code Example 2

#include <iostream>
#include <vector>

int main()
{
  std::vector<int> myvector;
  
  //add 2 to the back
  myvector.push_back(2);
  
  std::cout << myvector.back() << std::endl; //this will print 2
  
  myvector.push_back(46);
  std::cout << myvector.back() << std::endl; //prints 46
  
  return 0;
  
}

/*Output
2
46
*/

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