printmessage (); ?!

[MasseB]

Hello...

Trying to learn c++ and read the functions guide on c++ tutorials here on this site. I wondered, why do you have to use parenthesis after the printmessage in the bracket of the main function.

#include <iostream>
using namespace std;

void printmessage ()
{
  cout << "I'm a function!";
}

int main ()
{
  printmessage ();
}

[Homberto]

The parenthesis indicate that the function should be executed, and not treated as just another variable.
You can also pass parameters:

#include <iostream>
int add(int a, int b)
{
  return (a+b);
}
int main()
{
  std::cout << add(1,2) << std::endl;
  return 0;
}

[Ganado]

That's just the way C++ denotes a function, very common for many languages, not to mention for mathematics itself ( like f(x, y) ). It's relatively easy to parse because you know it has to be a function if it's a delimiting set of parentheses after a name.

Also, if your function actually had arguments that were passed into it, then that's where those arguments would go. ex: abs(-3)

If you want to get more technical, the name of the function itself is a pointer to the function, just as the name of an array is the pointer to that array. Don't worry about that if you haven't learned about pointers yet.