[英]Difference between (void)obj and void(obj)
According to http://en.cppreference.com/w/cpp/language/explicit_cast , C-style cast and functional cast are equivalent. 根据http://en.cppreference.com/w/cpp/language/explicit_cast,C风格的演员和功能演员是等效的。 However, see the following example:
但是,请参阅以下示例:
#include <array>
int main() {
std::array<int, 3> arr{};
(void)arr;
//void(arr);
}
While (void)arr compiles, void(arr) does not. 虽然(void)arr编译,但void(arr)却没有。 What have I missed?
我错过了什么?
If there are no ambiguities (eg other functions with the same name, macros..) involved, the following code declares and defines two int
variables 如果没有涉及的歧义(例如,具有相同名称的其他函数,宏...), 则以下代码声明并定义两个
int
变量
int a = 22;
int (b) = 33;
thus you're trying to create a void variable type (with an existing name) . 因此, 您正在尝试创建一个void变量类型(具有现有名称) 。
And that's wrong because: 那是错的,因为:
You're trying to use an existing name for another variable in the same scope 您正在尝试将现有名称用于同一范围内的另一个变量
虽然void(arr)
通常与(void)arr
相同,但在此上下文中它是一个定义,并且您尝试创建一个名为arr
的变量,该变量类型为void
,这是不允许的。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.