什么是“void（）;”作为一个单独的语句意味着C ++？ [英] What does "void();" as a separate statement mean in C++?

问题描述

这个程序如何编译得很好？

How does this program get compiled fine?

int main() {
    void();  // Does this create a "void" object here?
}

我已经在MSVC和GCC下测试过。但 void 是不完整的类型。当您对任何其他不完整的用户定义类型执行相同操作时，

I've tested both under MSVC and GCC. But void is an incomplete type. When you do the same for any other incomplete user-defined type,

class Incomplete;

int main() {
    Incomplete();  // Error saying "Incomplete" is incomplete.
}

推荐答案

void 类型是且始终是特殊的。它确实是不完整的，但是在许多情况下是允许的，其中通常期望完整类型。否则，例如，由于 void 类型的不完整性， void 函数的定义将无效。也可以编写 void 类型的表达式（对 void 函数的任何调用都是这种表达式的示例） 。

void type is and has always been special. It is indeed incomplete, but it is allowed in many contexts where a complete type is typically expected. Otherwise, for one example, a definition of a void function would be invalid because of incompleteness of void type. It is also possible to write expressions of void type (any call to a void function is an example of such expression).

即使在C语言中，也可以使用 void 的直接表达式）0 。你在代码中有什么只是一个C ++特定的语法的例子，它基本上是一样的事情：它产生类型 void 的无操作表达式。

Even in C language you can use immediate expressions of void type like (void) 0. What you have in your code is just an example of C++-specific syntax that does essentially the same thing: it produces a no-op expression of type void.

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