Initialization of reference member requires a temporary variable C++

Question

struct Div
{
   int i;
   int j;
};   

class A
{
    public:
             A();
             Div& divs;
};

In my constructor definition, I have

Answer 1

A reference must be initialised to refer to something; it can't refer to nothing, so you can't default-construct a class that contains one (unless, as others suggest, you define a global "null" value). You will need a constructor that is given the Div to refer to:

explicit A(Div &d) : divs(d) {}

If you want it to be able to be "null", then you need a pointer, not a reference.

Answer 2

For one, you can't have a NULL reference. As second, all variable references in a class must be initialized at construction time.

Answer 3

Plain and simple:

A reference can never be NULL.

Answer 4

class A
{
    Div & ref(Div div) { return div; }
    public:
       A() : divs(ref(Div())) {};
       Div& divs;
};

Answer 5

As noted in other posts, references (Div&) cannot be null. So the most straightforward change you can make is to provide a reference in the constructor and initialize your reference member. Like this,

class A
{
    public:
             A(Div& inDivs);
             Div& divs;

};

public A::A( Div& inDivs )
: divs( inDivs )
{}

Answer 6

References have to reference something. There is no such thing as a null reference in the C++ language. If the member may not have a value, then it should be a pointer, or a boost::optional or some type like that.

A reference must be initialized to reference a valid object.