What Is Rvalue Reference

Rvalue references is a small technical extension to the c language.

What is rvalue reference.

Lvalue reference and rvalue reference. Rvalue references are introduced in c 11 and rvalue references can do what lvalue references fails to do i e. C 0x has introduced a new type called rvalue reference denoted by placing a double ampersand after some type. 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. When the term reference is used it refers to both kinds of reference. Such rvalue reference lets you modify the value of a temporary object. Checks whether t is a rvalue reference type.

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. To declare a rvalue reference we need to specify two operator i e. To better distinguish these two types we refer to a traditional c reference as an lvalue reference. Here lvalueref2 is a lvalue reference so it cannot point to a rvalue.

According to the language specifications you are allowed to bind a const lvalue to an rvalue. 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. They are primarily meant to aid in the design of higer performance and more robust libraries.

Const int ref 10. Let s play a bit with this new toy. It s like removing the const attribute in the second line above. A rvalue reference can refer to rvalues.

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