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Quick Q: What does T&& mean in C++11? -- StackOverflow

By Blog Staff | Jan 12, 2013 10:07 AM | Tags: None

This question is so common it immediately got triple-digit upvotes on the question and answer:

What does T&& mean in C++11?

I've been looking into some of the new features of C++11 and one I've noticed is the double ampersand in declaring variables, like T&& var.

 

For a start, what is this beast called? I wish Google would allow us to search for punctuation like this.

What exactly does it mean?

 

At first glance, it appears to be a double reference (like the C-style double pointers T** var), but I'm having a hard time thinking of a use case for that.

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Anubhav said on Jan 14, 2013 09:53 PM:

The referenced article http://blogs.msdn.com/b/vcblog/archive/2009/02/03/rvalue-references-c-0x-features-in-vc10-part-2.aspx. mentions the following:

The modifiable rvalue reference, Type&& , is willing to bind to modifiable lvalues and modifiable rvalues, but not to const lvalues and const rvalues (which would violate const correctness).

I don't think this is correct.