Initialising reference in constructor C++

Question

I don't think is a duplicate question. There are similar ones but they're not helping me solve my problem.

According to this, the following is valid in C++:

class c { public:    int& i; }; 

However, when I do this, I get the following error:

error: uninitialized reference member 'c::i' 

How can I initialise successfully do i=0on construction?

Many thanks.

Answer 1

There is no such thing as an "empty reference". You have to provide a reference at object initialization. Put it in the constructor's base initializer list:

class c { public:   c(int & a) : i(a) { }   int & i; }; 

An alternative would be i(*new int), but that'd be terrible.

Edit: To maybe answer your question, you probably just want i to be a member object, not a reference, so just say int i;, and write the constructor either as c() : i(0) {} or as c(int a = 0) : i(a) { }.

Answer 2

A reference must be initialised to refer to something.

int a; class c { public:    int& i;    c() : i (a) {}; };