Difference of const and non-const Reference C++

Asked Apr 15 '16 at 13:08

Active Apr 15 '16 at 13:22

Viewed 55 times

const int& dummy = 5;

The code snippet above compiles without any errors / warnings using the g++ Compiler. Conversely using the code snippet

int& dummy = 5;

produces the following error code:

invalid initialization of non-const reference of type ‘int&’ from an rvalue of type ‘int’ int& dummy = 5;

Since the reference type from c++ is a lvalue reference I find it surprising that it is possible to assign an rvalue to it if is declared as const. Why?

edited Apr 15 '16 at 13:22

asked Apr 15 '16 at 13:08

clickMe

2

What is it you find surprising? – Captain Giraffe Apr 15 '16 at 13:10
4

[*GotW #88: A Candidate For the “Most Important `const`”*](https://herbsutter.com/2008/01/01/gotw-88-a-candidate-for-the-most-important-const/) – BoBTFish Apr 15 '16 at 13:10
@CaptainGiraffe since the reference type from c++ is an `lvalue reference` I find surprising that it is possible to assign an `rvalue` to it if is declared as `const` – clickMe Apr 15 '16 at 13:13
counter question: what would you expect to happen in the second case when you write `dummy = 7` (somewhere after the definiton) ? – 463035818_is_not_an_ai Apr 15 '16 at 13:14
3

SebTu: you forgot `int && dummy = 5;` in your tests – marcinj Apr 15 '16 at 13:16
Not sure what is the question. State a better question and we will find a dupe for it. – SergeyA Apr 15 '16 at 13:20
2

Because that's what the language standard says. By the way you cannot assign to a reference, you can only initialize one. – n. m. could be an AI Apr 15 '16 at 13:21
You have presumably written (or seen) a function with an argument like `foo(const int &bar)` before... and it has been able to compile when you say `foo(5)`... so does it not seem logical that a `const int &` can be initialized with a literal? – HostileFork says dont trust SE Apr 15 '16 at 13:24

Difference of const and non-const Reference C++

0 Answers0