Question

Is there anything wrong with writing a reference declaration and assignment in one statement. I have tried it using gcc and it seems to work.

int x = 10;
cout << "x = " << x << "\n";

int &y = x = 11;
cout << "x = " << x << "\n";
cout << "y = " << y << "\n";

gives me the expected output

x = 10
x = 11
y = 11

Is this expected to work on most compilers or will there be a portability issue?

Answer 1

In C++, there is an assignment operator, which can be used (at least in
principle) in any expression. Note that in:

int& y = x = 11;

The first = is not an operator; it is part of the syntax of the data
definition. What follows this = is an expression, which must result
in an lvalue of type int. Since x is an int, x = 11 has type
int. And the result of the built-in assignment operator is an lvalue,
referring to the object which was the target of the assignment, so
you’ve met the necessary conditions.

Of course, that doesn’t mean that it’s good code.