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Questions tagged [rvalue]

An rvalue is a temporary object (or subobject) or is a value not directly associated with an object.

Traditionally known as r-values since they generally appear on the right hand side of an expression; rvalues are temporary object whose lifetime does not extend past the current expression (unless bound to a an appropriate reference see ).

An rvalue is not directly associated with an object. Often a simple test is applied to determine if is an rvalue; "Is it named?"; if so, it is not an rvalue.

C++11 extended the original definition of an rvalue to include prvalues (pure rvalues) and xvalues (expiring values).

For a more general post on value categories, see this post on SO.

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rvalue not working for reference

I was studying about references and i was trying a program to pass an rvalue to a function as reference argument, like this. #include using namespace std; int fun(int &x) { return x; } int main() { cout << fun(10); return…
Arvind kr
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What could be mean the name rvalue reference?

I'm interested in why rvalue references are called exactly "rvalue references". How does it relate to rvalue, prvalue etc concepts. The section N3797::5/5 says: If an expression initially has the type “reference to T” (8.3.2, 8.5.3), the type is…
user2953119
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Is the value returned by a function in C++ is an rvalue? Failed to initialize an instance with copy/move constructor

I tried to initialize an instance with return value of a function. I expected it will call move constructor but the result is not. It seems that the return value are directly taken over by instance t. Because the t and return value in the function…
Zhaoze
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error: invalid initialization of non-const reference of type 'Vector2D&' from an rvalue of type 'Vector2D'

Here is the code, CodeBlocks indicates the error is on the line shwon: bool SoccerTeam::isPassSafeFromOpponent(Vector2D from, Vector2D target, const PlayerBase*…
Chris Parry
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C++ Benefit of rvalue reference constructors for simple types (Vector3, Matrix, etc)

Is there any advantage to using rvalue references if the object being passed does not have complex data? For example, would the following have any advantages over just using references? class Vector3 { public: float X, Y, Z; Vector3(const…
Alex Jorgenson
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What is LValues and RValues in objective c?

There are two kinds of expressions in Objective-C 1. RValue The term rvalue refers to a data value that is stored at some address in memory 2. LValue Expressions that refer to a memory location is called "lvalue" expression. An lvalue may appear…
Zar E Ahmer
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What is the exact meaning of an assignment operator?

I assume when we declare int a ; a=10;, then the compiler takes r-value & put it in it's l-value. At that time the l-value always treated as a address in the memory location i.e. a or any other variable in assignment operation at the left hand side…
SumS
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Does this rvalue signature pattern make sense?

Assume usually I want a copy of the object even if I get a reference. Assume these signatures are within a class scope so that both are seen. What are the pros and cons of doing this as opposed to just having a single push(const RingType& aData). If…
bjackfly
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Rvalue or Lvalue?

Given two variables: int x int* p and these expressions: *(&x+*p)+x &p+x *(&p-(int**)&x)+x *(&x+*(p+7)) For each expression find out if it is valid or not, if it an Rvalue expression or an Lvalue expression and what type it represents. I think…
Atlas80b
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C++11 rvalue object field

Can I have class/struct with rvalue field in c++11? Like this one: template struct RvalueTest{ RvalueTest(T&& value) : value( std::forward(value) ){} T&& value; }; Because in the following test: class Widget { public: …
tower120
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c++0x implicit conversion to non-scalar type

EDIT: Compiler version fixed. I'm trying out the new features of c++11 although I have Ubuntu 12.04 which includes gcc 4.6.3, thus only supporting c++0x. I have a general understanding problem with the following example class and it's constructors,…
poljpocket
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what is difference remove_reference or without it

i wrote a simple function that return object rvalue reference.But its not working right.But if i use std::move its working , i see only difference is remove_reference or what is? or my casting to rvalue is wrong ? template T&& mymove(T…
user2282169
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Convert temporary to reference in C++

I have the following code: #include #include #include #include int main() { llvm::Module *TheModule = new llvm::Module("my cool jit", llvm::getGlobalContext()); …
user868538
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How can I separate get and set access on operator[]?

EDIT I caused some confusion by referring to rvalues. I provide an example of what I want to do at the bottom. I want to separate these two calls: obj[key] = value; value = obj[key]; I tried using two operator[] overloads, hoping the const method…
payo
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Pre-increment operator returns lvalue or rvalue?

Going through other questions here, I've found that pre-increment operator in C returns rvalue, not lvalue. But, on trying the code below int a=35; printf("%d %d %d %d %d",a++,a,++a,a++,++a); I expected the output 38 39 38 36 36 But I get the…
MsPillai
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