Basic Vector Manipulation

Here is an example of basic vector manipulation

//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy

//This program shows how to create vectors, check size and capacity,

//change the value of the elements and finally clear the vector

#include <iostream>

#include <vector>



using namespace std;



int main()

{

  //Create a vector called vectorOne

  vector<int> vectorOne; //Note size is 0

  //Resize to 3 with default value 7

  vectorOne.resize(3,7);

  //Print the output to see the resize

  cout<<"Test 1"<<endl;

  for(unsigned i=0;i<vectorOne.size();i++)

  {

    cout<<"Element: "<<i<<"     Value: "<<vectorOne.at(i)<<endl;

  }



  //Resize further to 7 and new values default to 4

  vectorOne.resize(7,4);

  cout<<"\nTest 2"<<endl;

  for(unsigned i=0; i<vectorOne.size(); i++)

  {

    cout<<"Element: "<<i<<"     Value: "<<vectorOne.at(i)<<endl;

  }



  //Check what the size and capacity of the vector is

  cout<<endl;

  cout<<"Size of vectorOne is: "<<vectorOne.size()<<endl;

  cout<<"Capacity of vectorOne is: "<<vectorOne.capacity()<<endl;



  //Lets modify the values of these vectors

  for(unsigned i=0,j=22;i<vectorOne.size();i++,j+=i)

  {

    vectorOne.at(i)=j;

  }



  cout<<"\nTest 3"<<endl;

  for(unsigned i=0; i<vectorOne.size(); i++)

  {

    cout<<"Element: "<<i<<"     Value: "<<vectorOne.at(i)<<endl;

  }



  //Use reserve to reallocate vectorOne with enough storage for 10 elements

  vectorOne.reserve(10);

  cout<<"\nSize of vectorOne is: "<<vectorOne.size()<<endl;

  cout<<"Capacity of vectorOne is: "<<vectorOne.capacity()<<endl;



  //Try resizing to 15 and dont add any default values for the new elements

  vectorOne.resize(15);

  cout<<"\nSize of vectorOne is: "<<vectorOne.size()<<endl;

  cout<<"Capacity of vectorOne is: "<<vectorOne.capacity()<<endl;



  //Remove all elements of the vector

  vectorOne.clear();

  cout<<"\nVector Cleared"<<endl;

  cout<<"Size of vectorOne is: "<<vectorOne.size()<<endl;

  cout<<"Capacity of vectorOne is: "<<vectorOne.capacity()<<endl;

  cout<<endl;



  return 0;

}

The output of the program is as follows: