Function Overloading (Ad-hoc polymorphism) and default parameters

definition of  different functions with the same signature:

void helloWorld()
{
  cout << "Hello, World!";
}

void helloWorld(string world)
{
  cout << "Hello, " << world;
}

void helloWorld(float bla)
{
  cout << "Hello" << bla;
}


// will give you "duplicate symbol" error:
int helloWorld(float blabla)
{
  cout << "Hello" << bla;
}



signature of a function is function name and all parameter types, NOT parameter names and NOT return type

usage:
  helloWorld();
  helloWorld("Welt");
  helloWorld(static_cast<float>(6));
  helloWorld(6.0);


Default parameters:

void helloWorld2(string world="World")
{
  cout << "Hello, " << world;
}

would act as if:
void helloWorld2(string world)
{
  cout << "Hello, " << world;
}

void helloWorld2()
{
  helloWorld2("World");
}

usage:
  helloWorld2();  // prints: Hello, World
  helloWorld2("Welt"); // prints: Hello, Welt




int bla(int a, int b)
{
  return a*b;
}

float bla(double a, double b)
{
  return a/b;
}

int main() {
   cout << bla(1,2) << endl;   // print 2
   cout << bla(1,2.0) << endl;  // ambigious call (in case of gcc 3.3)
   cout << bla(1.0,2.0) << endl; // print 0.5
   return 0;
}