What are the rules for calling the superclass constructor?

Question

What are the C++ rules for calling the superclass constructor from a subclass one? For example, I know in Java, you must do it as the first line of the subclass constructor (and if you don't, an implicit call to a no-arg super constructor is assumed - giving you a compile error if that's missing).

Answer 1

Here is an example

using namespace std;

#include <iostream>

class X

{

protected:

int x;

public:

X(int n) { x = n; }

int GetX() { return(x); }

};

class Y: public X

{

protected:

int y;

public:

Y(int n, int x) : X(x) //calls parent constructor

{

y = n;

}

int GetY() { return(y); }

};

int main()

{

Y y(4,3);

cout << y.GetX() << endl;

cout << y.GetY() << endl;

return 0;

}