chrono::duration 下面的 typedef 是什么意思？

Question

我在阅读 article 时遇到了一段代码，作者说 "the C++ standard library provides the following type definitions:"

namespace std {
namespace chrono {
   typedef duration<signed int-type >= 64 bits,nano>        nanoseconds;
   typedef duration<signed int-type >= 55 bits,micro>       microseconds;
   typedef duration<signed int-type >= 45 bits,milli>       milliseconds;
   typedef duration<signed int-type >= 35 bits>             seconds;
   typedef duration<signed int-type >= 29 bits,ratio<60>>   minutes;
   typedef duration<signed int-type >= 23 bits,ratio<3600>> hours;
   }
}

我的问题是 signed int-type >= 64 bits 是什么意思？这是否意味着 signed int 减去 type？如果是这样，您如何解释？

Answer 1

这不是实际代码；它仅说明（以 "natural" 语言）在兼容实现中模板的类型参数需要什么。

因此 "signed int-type >= 64 bits" 表示 "any signed integer type with at least 64 bits"，但字母较少。

chrono::duration 下面的 typedef 是什么意思？

What does the following typedef mean in chrono::duration?

c++

chrono