This is a small bit of code to remind me of what I learned today about how to pass values to a parent class, as well as initialize member variables in the child class constructor.

class ParentClass
{
public:
	ParentClass(int x)
	{
		printf("ParentClass was passed: %i\n", x);
	}
};

class ChildClass : ParentClass
{
private:
	int y;
public:
	ChildClass(int x)
		: ParentClass(x), y(x)
	{
		printf("In ChildClass, y is: %i\n", x);
	}
};

int main(int argc, char* argv[])
{
	ChildClass childclass(42);
	return 0;
}

The output is:
ParentClass was passed: 42
In ChildClass, y is: 42

It’s not obvious to me how to split out the implementation from the interface in this case, however. Err… is “interface” and “implementation” the correct C++ lingo? That’s what it’s called in Objective-C. Hmm.