获得chrono :: duration的无符号整数毫秒 [英] Get an unsigned int milliseconds out of chrono::duration

问题描述

对于Winapi包装器，我想在给定调用持续时间内使用chrono。代码示例：

For a winapi wrapper I want to use chrono for a duration given to the call. The code example:

bool setTimer(std::chrono::duration<std::chrono::milliseconds> duration)
{
    unsigned int dwDuration = Do some chrono magic here

    SetTimer(m_hWnd,1,dwDuration,0);
}

dw持续时间必须以毫秒为单位。

dwDuration has to be in milliseconds.

第一个问题：如何做魔术。

First question: How do to the magic.

第二个问题：参数声明可以吗？

Second question: Is the parameter declaration okay?

推荐答案

类型名称为 std :: chrono :: milliseconds ，它的成员函数为 count（）返回毫秒数：

The name of the type is std::chrono::milliseconds, and it has a member function count() that returns the number of those milliseconds:

bool setTimer(std::chrono::milliseconds duration)
{
    unsigned int dwDuration = duration.count();
    return std::cout << "dwDuration = " << dwDuration << '\n';
}

在线演示：http://coliru.stacked-crooked.com/a/03f29d41e9bd260c

如果您想成为超级- pedantic，count（）的返回类型为 std :: chrono :: milliseconds :: rep

If you want to be ultra-pedantic, the return type of count() is std::chrono::milliseconds::rep

要处理小数毫秒，则类型将为 std :: chrono :: duration< double，std :: milli> （count（）的返回类型为然后加倍）

If you want to deal with fractional milliseconds, then the type would be std::chrono::duration<double, std::milli> (and the return type of count() is then double)

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