Question

Say I have some code like this:

class Foo
{
public:
  Foo(int v) : value(v) {}
  Foo() : Foo(42) {}
private:
  int value = 666;
};

Does the default ctor set value to 42 or 666? I guess I would hope for 42 since that is an explicit call but I could imagine the other way too.

How about with inheritance?

class Base
{
public:
  Base() { }
  virtual ~Base() { }
  virtual int f() = 0;
};

class Bar : public Base
{
public:
  Bar(int _i) : Base(), i(_i) { }
  Bar() : Bar(-1) { }
  virtual ~Bar() { }
  virtual int f() { }
private:
  int i = 777;
};

Again, I would hope for i == -1.

Thanks.

Answer 1

The in class body member initializer is just a default. If the member initializer list of a constructor initializes the member too, it takes precedence always.

This is specified by 12.6.2p9 in the C++11 spec.