Reference vs setting a local variable

Question

Consider the two cases:

Object& obj = *getObjectPtr();
Object obj = *getObjectPtr();

What is the difference between these two in C++?

This is covered in any introductory C++ book: http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list — Benjamin Lindley, Dec 17 '13 at 00:14

score 4 · Accepted Answer · answered Dec 17 '13 at 00:15

Line (1) is semantically equivalent to Object *obj_p = getObjectPtr(), and then using *obj_p. The reference behaves like a pointer, but without pointer syntax. More examples here: http://en.wikipedia.org/wiki/Reference_%28C++%29

Line (2) will cause a new Object to be created, and the Object at the memory address getObjectPtr() to be copied into it via (probably) Object's copy constructor.

score 1 · Answer 2 · edited Dec 17 '13 at 01:56

1

Object& obj = *getObjectPtr(); - obj will hold a reference to the original object that is returned by getObjectPtr().

Object obj = *getObjectPtr(); - obj will hold a copy of the original object that is returned by getObjectPtr().

edited Dec 17 '13 at 01:56

Remy Lebeau

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answered Dec 17 '13 at 00:25

Billie

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The first refers to the object *inside the function*, the second makes a copy of the object. – Thomas Matthews Dec 17 '13 at 00:26

Reference vs setting a local variable

2 Answers2