What Is Rvalue Reference

Lvalue reference and rvalue reference.

What is rvalue reference.

Rvalue references are introduced in c 11 and rvalue references can do what lvalue references fails to do i e. To declare a rvalue reference we need to specify two operator i e. They are primarily meant to aid in the design of higer performance and more robust libraries. Rvalue references allow programmers to avoid logically unnecessary copying and to provide perfect forwarding functions.

Provides the member constant value which is equal to true if t is a rvalue reference type. So the following snippet works like a charm. To better distinguish these two types we refer to a traditional c reference as an lvalue reference. Rvalue references are a feature of c that was added with the c 11 standard.

Otherwise value is equal to false. A rvalue reference can refer to rvalues. Checks whether t is a rvalue reference type. Const int ref 10.

Let s play a bit with this new toy. According to the language specifications you are allowed to bind a const lvalue to an rvalue. Here lvalueref2 is a lvalue reference so it cannot point to a rvalue. C 0x has introduced a new type called rvalue reference denoted by placing a double ampersand after some type.

It s like removing the const attribute in the second line above. When the term reference is used it refers to both kinds of reference. The behavior of a program that adds specializations for is rvalue reference or is rvalue reference v since c 17 is undefined. Such rvalue reference lets you modify the value of a temporary object.

An rvalue reference is a compound type very similar to c s traditional reference.