Help with date math

General
1

I am working on an app that is counting down to a student’s test date. How is this best accomplished? I am using this below, but if the test date is in 2017 or further, this treats the days until the test as if it were the same year

d.Day = rs3.Field("MyExamDate").DateValue.DayOfYear - d.Day

If I choose a test date of 2016-08-15, then the days until is showing as 6 (probably figuring in today). When I choose 2017-08-15 (next year), it shows 5 days until, so this is not right.

What is the setup to account for future years and count the number of days?

Also, I am using the Calendar Picker from the examples. Is there a way to not choose a date earlier than today?

2

Use TotalSeconds to calculate the difference in the dates and then use the date object to make it readable.

dim dtDaysRemain as Date
dim dtToday as new Date
dtDaysRemain.TotalSeconds = dtTestDate.TotalSeconds - dtToday.TotalSeconds

You can then use dtDaysRemain to get the readable stuff like Days.

3

Tim, you method will return a DATE not # of days (unless it happens to be less than 31)…
32 days would be something like “01-Feb-1970”

dim daysRemaining as integer
daysRemaining = ceil((dtTestDate.TotalSeconds - dtToday.TotalSeconds)/(24*60*60))
4

You rock Dave! Works like a charm!

5

Ah well, I pulled it from memory.
I see that it wouldn’t work for any timeframe longer than a month.

6

Just for the record, for anybody interested in the subject of time difference, there was a very long thread a couple years ago, which among other things, showed the difference between counting days in Europe and in the US.

https://forum.xojo.com/15374-getting-the-date-difference-in-years-months-days/0

7

This is how you could do it using the new framework:

Dim testDate As New Xojo.Core.Date(2017, 8, 15, Xojo.Core.TimeZone.Current)
Dim interval As Xojo.Core.DateInterval
interval = testDate - Xojo.Core.Date.Now
  
MsgBox("The test is " + interval.Years.ToText + " years, " + interval.Days.ToText + " days and " + interval.Hours.ToText + " hours from now.")