What Is Rvalue Reference

Let s play a bit with this new toy.

What is rvalue reference. It s like removing the const attribute in the second line above. Rvalue references are a feature of c that was added with the c 11 standard. Otherwise value is equal to false. According to the language specifications you are allowed to bind a const lvalue to an rvalue.

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

C 0x has introduced a new type called rvalue reference denoted by placing a double ampersand after some type. Here lvalueref2 is a lvalue reference so it cannot point to a rvalue. They are primarily meant to aid in the design of higer performance and more robust libraries. Provides the member constant value which is equal to true if t is a rvalue reference type.

Rvalue references is a small technical extension to the c language. The behavior of a program that adds specializations for is rvalue reference or is rvalue reference v since c 17 is undefined. So the following snippet works like a charm. To declare a rvalue reference we need to specify two operator i e.

When the term reference is used it refers to both kinds of reference. To better distinguish these two types we refer to a traditional c reference as an lvalue reference. Rvalue references are introduced in c 11 and rvalue references can do what lvalue references fails to do i e. Such rvalue reference lets you modify the value of a temporary object.

Const int ref 10.