C # datediff and dateadd

Address: http://www.wlm.so/Article/Detail/lmb49q5hxpqyi00000

I just searched for datediff in C # on Baidu. I was shocked to see that C # didn't have this function.

There are also various user-defined functions.
In desperation, write a datetime variable by yourself. Look at it, yo, there are adddays or something. This is not an issue.
C # There are such perfect adddays, addmonths and other functions. What else do I need dateadd or something.
After testing, positive and negative numbers are acceptable.
Datetime endtime = new datetime (2014, 12, 1). addmonths (1). adddays (-1 );
Get it done, and close the job.

Address: http://www.wlm.so/Article/Detail/lmb49q5hxpqyi00000

C # datediff and dateadd