Hello world C++91, C++98, C++03, C++11, C++14, C++17

// Hello world program
/* Languages:
    - C++91 ("The C++ Programming Language, Second Edition", by Bjarne Stroustrup, 1991)
    - C++98 (ISO/IEC 14882:1998)
    - C++03 (ISO/IEC 14882:2003)
    - C++11 (ISO/IEC 14882:2011)
    - C++14 (ISO/IEC 14882:2014)
    - C++17 (ISO/IEC 14882:2017)
*/

#include <iostream>

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