Vectors in C++

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    // create an empty vector
    vector<int> myVector;

    // insert one element
    myVector.push_back(5);

    // insert another element
    myVector.push_back(4);

    // insert more elements
    myVector.push_back(1337);
    myVector.push_back(42);
    myVector.push_back(31415);

    // insert an element which was there before
    myVector.push_back(5);

    // get the number of elements (length/size) of the vector
    cout << myVector.size() << endl;

    // get the third element
    cout << "third element: " << myVector[2] << endl;

    // removes the element at position number 6
    myVector.erase (myVector.begin()+5);

    // removes the element with the value 4
    myVector.erase(remove(myVector.begin(), myVector.end(), 4),
                    myVector.end());

    // iterate over the vector
    vector<int>::iterator myIt;
    for(myIt=myVector.begin(); myIt != myVector.end(); myIt++){
        cout << *myIt << " ";
    }
    cout << endl;

    return 0;
}

third element: 1337
5 1337 42 31415

// create a vector with 100 zeroes
vector<int> myVector (100);

// create a vector which has 42 times the integer 100
vector<int> myVector (42, 100);

#include <iostream>
#include <vector>

using namespace std;

int main() {
    // create an empty vector
    vector< vector<int> > myVector (4);

    // add elements
    myVector[0].push_back(1);
    myVector[0].push_back(2);
    myVector[1].push_back(3);

    // iterate over the vector
    vector< vector<int> >::iterator myIt;
    vector<int>::iterator innerIt;
    for(myIt=myVector.begin(); myIt != myVector.end(); myIt++){
        cout << "Inner vector: ";
        for (innerIt=myIt->begin();innerIt!=myIt->end();innerIt++) {
            cout << *innerIt << " ";
        }
        cout << endl;
    }

    return 0;
}

Inner vector: 1 2
Inner vector: 3
Inner vector:
Inner vector:

vector<int> myInnerVector(5, 3);
vector<vector<int> > myVector(8,myInnerVector);

Inner vector: 3 3 3 3 3
Inner vector: 3 3 3 3 3
Inner vector: 3 3 3 3 3
Inner vector: 3 3 3 3 3
Inner vector: 3 3 3 3 3
Inner vector: 3 3 3 3 3
Inner vector: 3 3 3 3 3
Inner vector: 3 3 3 3 3

vector< vector<int> > myVector(8, vector<int>(5, 3));

#include <algorithm>
#include <vector>

using namespace std;

int main () {
  vector<int> myvector;
  vector<int>::iterator it;

  // set some values:
  for (int i=1; i<10; ++i) myVector.push_back(i); // 1 2 3 4 5 6 7 8 9

  reverse(myVector.begin(),myVector.end());       // 9 8 7 6 5 4 3 2 1

  // print out content:
  cout << "myVector contains:";
  for (it=myVector.begin(); it!=myVector.end(); ++it)
    cout << " " << *it;

  cout << endl;

  return 0;
}