// Similar to array-1.c discussed earlier.

#include <iostream>
#include <string>
#include <vector>

// Using declarations:
using std::string;
using std::vector;
using std::cout; using std::endl;

int main(){
  // Vector construction:
  vector<double> a;  // An empty vector of element type double
  double sum;

  // Adding elements to the back end:
  for (vector<double>::size_type i = 1; i <= 5; i++)
    a.push_back(i);

  // Mutation of an EXISTNG ELEMENT:
  a[1] = 2.2;

  // Sum up the elements - in a simple for-loop:
  sum = 0.0;
  for (int i = 0; i < a.size(); i++){
    sum += a[i];
  }
  cout << "Sum = " << sum << endl;  // 15.2

  // Sum up the elements - with iterators:
  sum = 0.0;
  for (vector<double>::iterator iter = a.begin();
       iter != a.end();
       iter++){
    sum += *iter;
  }
  cout << "Sum = " << sum << endl;  // 15.2
}