日期差异编码 [英] coding of datedifference

问题描述

我正在开发图书馆管理软件
所以我需要在发行书的日期和退还书的日期之间的日期差，以便我可以很好地进行计算.
这两个日期都应直接从系统中获取，而不是从用户端获取.所以我需要一个代码.

i am working on library management software
so i need the difference of date between date on which book is issued and date on which book is returned so that i can calculate fine.
both date should be taken from system directly,not from user side.so i need a code.

推荐答案

然后您可以使用GetSystemTimeAsFileTime [

Then you can use the GetSystemTimeAsFileTime[^] function.

FILETIME is a struct, but you can use an __int64 since the memory layout matches.

__int64 currentDateAndTime;
GetSystemTimeAsFileTime((LPFILETIME)&currentDateAndTime);

SYSTEMTIME systime;
FileTimeToSystemTime((LPFILETIME)&currentDateAndTime,&systime);

在__int64上进行计算非常容易...

转换为系统时间 [

Doing the calculations on an __int64 is pretty easy ...

Convert to SYSTEMTIME[^] when you need to access the various elements of the date and time information.

Best regards
Espen Harlinn

您没有指定它是用于MFC C ++还是其他东西，因此这里是它的MFC版本...

1.获取图书发行的日期/时间:

You did not specify whether it is for MFC C++ or something else, so here''s the MFC version of it...

1. Get date/time when the book was issued:

CTime bookIssued = CTime::GetCurrentTime();

2.获取退还书籍的日期/时间:

2. Get date/time when the book was returned:

CTime bookReturned = CTime::GetCurrentTime();

3.计算天数差异:

3. Calculate the difference in days:

CTimeSpan diff = bookReturned - bookIssued;
__int64 days = diff.GetDays();

您的变量days现在具有所需的天数.

Your variable days now has the number of days that you need.

在 ^ ]和 System.TimeSpan [ ^ ].

[edit]
作为Espen& Vitaly指出这是一个C ++问题，所以对不起，我的回答不相关.但是，使用 time() [ difftime() [

Read up on System.DateTime[^] and System.TimeSpan[^].

[edit]
As Espen & Vitaly pointed out this is a C++ question so my answer is not relevant, sorry. However using the time()[^] and difftime()[^] functions of the CRT library you can achieve the same objectives.
[/edit]

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