Examples of using Rvalue in English and their translations into Vietnamese
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Colloquial
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Ecclesiastic
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Computer
Those places are defined by the rvalue category;
An lvalue is not an rvalue and an rvalue is not an lvalue.
It does not mean that the reference itself is an rvalue!
Unless the rvalue is due to unnamed rvalue reference…".
In C++03, an expression is either an rvalue or an lvalue.
People also translate
A prvalue(“pure” rvalue) is an rvalue that is not an xvalue.
We still have the terms lvalue and rvalue that are compatible with C++98.
Since an rvalue is going to die at the end of an expression, you can steal its data.
So, the left leg of the W is lvalue and glvalue andthe right leg is prvalue and rvalue.
Rvalue references to functions are treated as lvalues whether named or not.
It's very tempting to read the int&& as a type andconclude that a is an rvalue.
If the argument is an rvalue of type X, T is deduced to be X, hence T&& means X&&.
From a user's perspective, the meaning of it is that std::forward is a conditional cast to an rvalue.
An rvalue is a temporary object, which is going to be destroyed at the end of the expression.
Note that even though std:: move( a) is an rvalue, its evaluation does not create a temporary object.
An rvalue of class type is an expression whose evaluation creates a temporary object.
If we would like to understand the concepts of the new expression valuecategories we have to be aware of that there are rvalue and lvalue references.
Since its rhs argument is an rvalue, we know it's not needed any longer and we can steal its value.
An rvalue(so called, historically, because rvalues could appear on the right-hand side of an assignment expression) is an xvalue, a.
That is,sometimes we want the compiler to treat an lvalue as if it were an rvalue, so it can invoke the move constructor, even though it could be potentially unsafe.
It's not an rvalue(old-style), because it can be on the left side of an equation(things are actually a bit more complicated, see this question and the comments below).
If you look at its type, you see an rvalue reference, but an rvalue reference simply means"a reference that is bound to an rvalue";
The expression E belongs to the rvalue category if and only if E belongs to the xvalue category, or to the prvalue category.
Only with both of lvalue and rvalue, the move semantics, perfect forward and rvalue reference still are work well.
They do, like intended, prefer rvalue references during overloading, and won't bind to non-const lvalue references.
What previously was an rvalue(literals, objects created by casts to non-reference types) now becomes an prvalue.
C++0x introduces a new mechanism called"rvalue reference" which, among other things, allows us to detect rvalue arguments via function overloading.
Note that this definition means that the expression E belongs to the rvalue category if and only if E refers to an entity that has not had any identity that makes it accessible outside of E YET.
I observed that the standard library wording uses rvalue to mean m(the generalization), so that to preserve the expectation and text of the standard library the right-hand bottom point of the W should be named rvalue.