Question

My C++ overloading does not act as I assume it should:

#include "Node.h"
#include <iostream>

Node::Node()
{
    cout << "1" << endl;
    Node(Game(), 0.0);
}

Node::Node(double v)
{
    cout << "2" << endl;
    Node(Game(),v);
}

Node::Node(Game g, double v)
{
    cout << "3" << endl;
    numVisits = 0;
    value = v;
    game = g;
}

And the output from:

Node n(16);
cout << n.value << endl;

is 0, when it should be 16.

What am I doing incorrectly?

Answer 1

Node(Game(),v); in your constructor doesn’t do what you expected. It just creates a temporary without using it and makes no effect. Then it immediately destructs that temporary when control flows over the ;.

The correct way is initializing the members in each constructor. You could extract their common code in a private init() member function and call it in each constructor like the following:

class Foo {
    public:
        Foo(char x);
        Foo(char x, int y);
        ...
    private:
        void init(char x, int y);
};

Foo::Foo(char x)
{
    init(x, int(x) + 3);
    ...
}

Foo::Foo(char x, int y)
{
    init(x, y);
    ...
}

void Foo::init(char x, int y)
{
    ...
} 

C++11 will allow constructors to call other peer constructors (known as delegation), however, most compilers haven’t supported that yet.