Limiting date input?

[ABOU]

On my Client input form i want to limit the minimum age to 18 using dates as opposed to numbers.

I have been thinking on how to go about this, i thought that a datecompare would be the way to go, but i have no idea how to compare 2 dates that will be changing with each new day.

Would it be a viable idea to take the DOBDateTimePicker min date property and increment it somehow each new day, with it preset to 03/05/1990 (18 years back from today).

Or is there a better way to go about this?

 

[Rocksteady]

Can't you just do

If Date.Now.Subtract(Their Birthday as Datetime) .TotalYears >= 18 Then

Bla Bla Bla

Or whatever.

 

[JohnH]

This date 18 years ago:

Dim d As Date = Date.Now
d = New Date(d.Year - 18, d.Month, d.Day)

 

[ABOU]

Thanks i was able to work that perfectly, I need to show use of an error provider so working that in to an If statement sorted it

 

[jmcilhinney]

This date 18 years ago:

Dim d As Date = Date.Now
d = New Date(d.Year - 18, d.Month, d.Day)

Dim d As Date = Date.Today.AddYears(-18)

 

[InertiaM]

Dim d As Date = Date.Today.AddYears(-18)

This is also a slightly safer way than John's way. If you, for example, do

        Dim d As Date = New Date(2008, 3, 31)
        d = New Date(d.Year, d.Month + 1, d.Day)

it will throw an ArgumentOutOfRangeException as the date is invalid - April does not have 31 days.

Running it as

        Dim d As Date = New Date(2008, 3, 31)
        d = d.AddMonths(1)

will return 30th April 2008.

 

[JohnH]

Yes, I missed the AddYears method because I didn't think it'd span years, TimeSpan doesn't. But John's ways is not to add 1 to a Month or a Day, at least not without validating first. There's no end to years in either direction, except those that also AddYears raises ArgumentOutOfRangeException for.