C++

#include <iostream>

main()
{
std::cout << "Hello World!" << std::endl;
}

What am I doing wrong here? The cmd just flashes and close. It doesn't display hello world.

#include <iostream>
#include <cstdlib>

using namespace std;

int main (void)
{
   printf("Hellow, World!\n");
   system("pause");
   return 0;
}

This is epic fail code.