What Is Rvalue Reference

Const int ref 10.

What is rvalue reference.

An rvalue reference is a compound type very similar to c s traditional reference. According to the language specifications you are allowed to bind a const lvalue to an rvalue. So the following snippet works like a charm. C 0x has introduced a new type called rvalue reference denoted by placing a double ampersand after some type.

Lvalue reference and rvalue reference. When the term reference is used it refers to both kinds of reference. Provides the member constant value which is equal to true if t is a rvalue reference type. Rvalue references are a feature of c that was added with the c 11 standard.

Such rvalue reference lets you modify the value of a temporary object. To declare a rvalue reference we need to specify two operator i e. Rvalue references is a small technical extension to the c language. Rvalue references are introduced in c 11 and rvalue references can do what lvalue references fails to do i e.

It s like removing the const attribute in the second line above. Checks whether t is a rvalue reference type. Here lvalueref2 is a lvalue reference so it cannot point to a rvalue. Invalid initialization of non const reference of type int from an rvalue of type int gcc complains about the reference not being const namely a constant.

They are primarily meant to aid in the design of higer performance and more robust libraries. Let s play a bit with this new toy. The behavior of a program that adds specializations for is rvalue reference or is rvalue reference v since c 17 is undefined. Rvalue references allow programmers to avoid logically unnecessary copying and to provide perfect forwarding functions.

What makes rvalue references a bit difficult to grasp is that when you first look at them it is not clear what their purpose is or what problems they solve.