将C＃日期时间对象转换为Excel日期格式

Question

I need to convert a C# datetime object into the dreaded Excel date format: https://datapub.cdlib.org/2014/04/10/abandon-all-hope-ye-who-enter-dates-in-excel/

ie number of days since 1 Jan 1900 expressed as a floating point number.

Is there any way to do it without resorting to DIY code? I need it in order to create Excel-friendly CSV exports

Googling around I didn't find anything useful except that good blog post

Answer 1

Excel dates use the OLE Automation date format. You can retrieve it with DateTime.ToOADate

OA Dates are a double whose integer part is the date offset from 30 December 1899 (ie earlier dates are negative) and fractional part is the time divided by 24.

This type was used a lot in the COM/VB6 days. Nowadays it's needed for Excel and when you need to call COM APIs that expect dates or variants with a date content.

Answer 2

您可以使用以下方法将Excel日期转换回C＃DateTime

return DateTime.FromOADate(SerialDate);