Invalid initialization of non-const reference to type from a temporary of type

Question

My class structure is as follows:

Test_Camera.h:

class Test_Camera : public Camera_Interface { public: Test_Camera (string const& aName); ...

Test_Camera.cpp

Test_Camera::Test_Camera(string const& aName) : Camera_Interface(0, 0, 0, 0), name(aName)

In my code that instantiates a Test_Camera object I have 2 scenarios. The first compiles fine, but the second doesn't and I can't figure out why.

Test_Camera cam ("cam"); // This compiles Test_Camera& cam ("cam"); // This does not compile

When I try to compile the second example I get an error:

error: invalid initialization of non-const reference to type 'Test_Camera&' from a temporary of type 'const char*'

I also tried:

string name = "cam"; Test_Camera& cam (name); //does not compile

masoud · Accepted Answer · 2013-04-17 13:56:14Z

6

References should refer to an existing object:

Test_Camera cam ("cam"); Test_Camera &cam_ref = cam;

answered Apr 17, 2013 at 13:56

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3 Comments

Why is it that when I do Test_Camera& cam (); this compiles?

@Redek: Because that's a function prototype. The compiler assumes that cam() is function returning Test_Camera&.

@phresnel Thank you, that's where my confusion was.. I thought that it was calling the no-argument constructor. Makes a lot more sense now!