Xojo.Core.Date.DayOfYear
From Xojo Documentation
Read-Only Property (As Integer )
The number of days into the year, 1-based. January 1st is 1.
Sample Code
Get the day of the year:
To check to see if a year is a leap year, you can create a date on the last day of the year (Dec 31) and then check DayOfYear to see if it is greater than 365. For example: