是static_cast< T>（...）编译时还是运行时？ [英] Is static_cast<T>(...) compile-time or run-time?

问题描述

static_cast< T>（...）是在编译时或运行时完成的吗？我在Google周围搜索，但得到了不同的答案。

Is static_cast<T>(...) something that gets done at compile-time or run-time? I've googled around but I got different answers.

此外， dynamic_cast< T>（...）显然是运行时-但是 reinterpret_cast< T>（...）？

Also, dynamic_cast<T>(...) is obviously runtime - but what about reinterpret_cast<T>(...)?

推荐答案

取决于您要投射的内容还有什么例如。 static_cast< std :: string>（ Hello）最终调用 std :: string 构造函数。

Depends on what you are casting to what else. E.g. static_cast<std::string>("Hello") ends up calling std::string constructor.

我想不起，在任何情况下 reinterpret_cast 都需要生成实际的机器指令。只是告诉编译器：采用这种位模式，并认为它是这种类型的值。

Off the top of my head, I can't think of any case where reinterpret_cast would need to generate actual machine instructions. It's just telling the compiler: take this bit pattern, and believe it to be a value this type.

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