c++ double & usage

Question

Sometimes I see function declare like this:

void foo(vector<some type>&& inputs);

What is the major reason to use && instead of &?

Probably the two most common major reasons are to allow move semantics and perfect forwarding. — Jerry Coffin, Mar 04 '13 at 05:20
@Ben, yes, it does indeed look like a duplicate. I think my answer's better than that thread's answer though! — Dave, Mar 04 '13 at 05:23

score 3 · Accepted Answer · answered Mar 04 '13 at 05:21

This is a new thing in C++11 called rvalue references.

You can read a great introduction to them here: http://thbecker.net/articles/rvalue_references/section_01.html

Essentially, it says it will be a reference to an object which can be destroyed without causing problems, and is used to optimise certain operations such as copy constructors (which can be changed for a swap if the other object can be destroyed).

c++ double & usage

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