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如果 d > 255，为什么 std::chrono::day 存储值未指定

[英]Why std::chrono::day stored value is unspecified if d > 255

原文 2020-11-23 12:22:03 5 1 c++/ literals/ c++20/ chrono

Quoted from std::literals::chrono_literals::operator""d引自std::literals::chrono_literals::operator""d

A std::chrono::day storing d.一个 std::chrono::day 存储 d. If d > 255, the stored value is unspecified.如果 d > 255，则未指定存储值。

What is the rationale behind this limit ?这个限制背后的原理是什么？

1 个解决方案

The literal can't store more than std::chrono::day itself can, which is 0 - 255 .文字不能存储超过std::chrono::day本身可以存储的数量，即0 - 255 。 This allows it to be implemented as a 1 byte data type, which as it usually will only store values between 1 and 31 is sufficient.这允许将其实现为 1 字节数据类型，因为它通常只存储 1 到 31 之间的值就足够了。

If you're looking for a data type to store a duration of an arbitrary number of days use std::chrono::days instead.如果您正在寻找一种数据类型来存储任意天数的持续时间，请改用std::chrono::days 。

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