使用字符串流格式化日期 [英] Formatting dates with stringstream

问题描述

我想避免在我的 C++ 代码中使用 sprintf，所以我只能使用 C++ 中的 std 字符串，但我还没有找到替换它的方法.我目前使用 sprintf 来格式化日期和时间，如下所示:

I want to avoid the usage of sprintf in my C++ code so I can use only std strings from C++, but I haven't found the way to replace it yet. I currently use sprintf to format dates and times like this:

char myDate[DATE_LENGTH]{};
sprintf(myDate, "%4d-%02d-%02d %02d:%02d:%02d", year, month, day,
        hour, minute, second);

通过这种方式，我将为每个整数获得固定长度，如果需要，可以使用前导零.

In this way, I will get a fixed length for each integer, with leading zeros if needed.

我已经搜索了如何用 stringstream 替换它，并找到了这个:

I have searched how to replace this with stringstream, and found this:

std::ostringstream ss;
ss << std::setw(5) << std::setfill('0') << 12 << "\n";

但这只会格式化其中一个整数.我需要为每个日期和时间组件执行此操作，然后将它们全部附加在一起.所以要替换一行 C 风格的代码，我需要更多的新代码.

But this only would format one of the integers. I would need to do this for each date and tiem component and then append all of them together. So to replace one line of C-style code, I would need much more new code.

没有比这更好的方法了吗?

Is not there any way to do better than this?

推荐答案

(1) 定义您自己的数据时间类.

(1) Define your own datatime class.

(2) 为其定义operator <<() 和operator >>().在这些函数中，使用std::time_put和std::time_get facet来实现.

(2) Define the operator <<() and operator >>() for it. In these function, use std::time_put and std::time_get facet to implement.

(3) 如果std::time_put和std::time_get不能满足你的需求，你可以通过继承定义你自己的time_put/get facet, 以及其他辅助方面，例如 date_time 格式管理器(如有必要).

(3) If the std::time_put and std::time_get can't satisfy your needs, you can define your own time_put/get facet by inheriting them, and other assistant facet such as date_time format manager if necessary.

PS:如果您使用的是 c++11，std::time_put::put() 和 std::time_get::get() 可能是满意.

PS: If you're using c++11, std::time_put::put() and std::time_get::get() may be satisfied.

祝你好运！

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