说明符和限定符之间的相关性？ [英] Correlation between specifier and qualifier?

问题描述

const 和 volatile 被称为 cv-qualifier

说明符和限定符之间的正义是什么c $ c>（ cv-qualifier ）？

是否必须有限定符只有一个左值？

Is it necessarry that qualifier is with an lvalue only?

除 cv-qualifier 之外的限定符是什么？

What are qualifiers other than cv-qualifier?

推荐答案

大部分没有意义。

和限定符是在C ++标准中定义的。 例如，声明中的类型说明符可以包含 cv-qualifiers 。我没有看到为这个主题的标准引用一切的原因。

Specifier and qualifier are defined in the C++ standard. Qualifier is just an integral part of a specifier. For example, type specifier in a declaration can include cv-qualifiers. I don't see the reason to quote everything from the standard on this topic.

Cv限定符不限于lvalue。类类型的Rvalues也可以是cv限定。

Cv-qualifiers are not restricted to lvalues. Rvalues of class types can also be cv-qualified. It is possible to cv-qualify an rvalue of non-class type, but it will have no effect and will be ignored.

的使用可以通过cv-qualify非类型的右值来实现， const 限定符在你的示例中显示的 foo 只是一个句法形式，这实际上意味着const-qualifier应用于隐含 方法的参数： const A * this 。也就是说在这种情况下，它确实符合一个左值，但它是 * this ，而不是 foo 。

The use of const qualifier that you show in your example with foo is just a syntactic form, which actually means that the const-qualifier is applied to the implied this parameter of the foo method: const A* this. I.e. in this case it does indeed qualify an lvalue, but it is *this, not foo.

术语限定词也出现在限定名的上下文中。像 some_class :: some_member （或 some_namespace :: some_name ）的名称称为限定名称和 some_class :: 部分是限定符。

The term qualifier also appears in the context of qualified names. Name like some_class::some_member (or some_namespace::some_name) are called qualified names and the some_class:: part is a qualifier.

是一个左值，那么你可以修改它是完全不正确的。有可修改的左值和不可修改的左值。一个声明为 const int i = 5 的对象是一个左值，但你不能修改它。普通函数在C ++中也是左值，但你不能修改函数。

The idea that if something is an lvalue then you can modify it is totally incorrect. There are modifiable lvalues and non-modifiable lvalues. An object declared as const int i = 5 is an lvalue, yet you can't modify it. Ordinary functions are also lvalues in C++, yet you can't modify a function.

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