Are parent class constructors called before initializing variables?

Question

Are parent class constructors called before initializing variables, or will the compiler initialize the variables of the class first?

For example:

c         


        

Answer 1

Just as some advice, you can usually just test things like this out yourself if you're not sure:

#include 
using namespace std;

class parent {
protected:
  int a;
public:
  parent() : a(123) { cout << "in parent(): a == " << a << endl; };
};

class child : public parent {
  int b;
public:
            // question: is parent constructor done before init b?
  child() : b(456), parent() { cout << "in child(): a == " << a << ", b == " << b << endl; };
};

int main() {
  child c;
  return 0;
}

prints

in parent(): a == 123
in child(): a == 123, b == 456