#include <iostream>

// Why does this source code not compile?
//
// First, examine the code and try to
// identify the problem without compiling it.
//
// If you cannot find the problem, compile
// the code and use the compiler's error
// message as a hint.
//
// If you still cannot find the problem,
// scroll down.

// Function declaration
int main();

// Function definition
int main() {
    std::cout "Hello World!" << std::endl;

    return 0;
}


















































// When printing to the screen using
// 'std::cout', the stream insertion operator
//
//     <<
//
// must appear between 'std::cout' and the
// value to be printed. Thus,
//
//     std::cout "Hello World!" << std::endl;
//
// should be
//
//     std::cout << "Hello World!" << std::endl;
//
// Exercise: Insert the missing '<<', but then
// remove the second '<<'. How does the compiler's
// error message change? Can you explain why?