How to check if a datetime is exactly a month before today´s date in c#

Question

I'm making a program for project control, and I´d like it to validate the start date using the condition that it has to be atleast a month before today. I pretty much have no idea what im doing when it comes to datetime so any help would be appreciated. And before you ask, no it´s not homework, I'm teaching myself c#.

a month, like if today is 18, I´d like the start date to be at least a month before today, 18 october for example. — L. de la Cruz, Nov 18 '15 at 16:49
Look at the answer from Jon Skeet here: http://stackoverflow.com/questions/1525990/calculating-the-difference-in-months-between-two-dates — Fruchtzwerg, Nov 18 '15 at 16:50
https://msdn.microsoft.com/en-us/library/system.datetime%28v=vs.110%29.aspx?f=255&MSPPError=-2147217396 (DateTime on MSDN) Documentation on DateTime — Whiplash450, Nov 18 '15 at 16:54

score 0 · Answer 1 · answered Nov 18 '15 at 16:50

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Do you mean like this date == DateTime.Today.AddMonths(-1);?

answered Nov 18 '15 at 16:50

coding lion

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Just to clarify, this will only match if `date` is also truncated to the `.Today` part, if it includes a legitimate time part, this check will fail. – Ron Beyer Nov 18 '15 at 16:50
@RonBeyer "Truncate" is misleading. You can't truncate time in .NET. You can only set it to a specific time--midnight in this case. (Nit-picky, I know.) – Kenneth K. Nov 18 '15 at 17:06

score 0 · Answer 2 · answered Nov 18 '15 at 16:50

DateTime today = DateTime.Now.Date
DateTime oneMonthAgo = today.AddMonth(-1);
bool isOk = startDate <= oneMonthAgo; // or < ? define exact condition for your requirement

DateTime class has plenty of useful method to deal with Date in many way: use them!

How to check if a datetime is exactly a month before today´s date in c#

2 Answers2