Hello world

#include <iostream>

/***
using namespace std;

int main()
{
    cout << "Hello world!" << endl;
    return 0;
}

***/

/***

// my second program in C++
#include <iostream>
using namespace std;

int main ()
{
  cout << "Hello World! ";
  cout << "I'm a C++ program";
}
***/
/***

// my second program in C++
#include <iostream>

int main ()
{
  std::cout << "Hello World! ";
  std::cout << "I'm a C++ program";
}
***/