DateInterval.Days

From Xojo Documentation

Property (As Integer )
aDateInterval.Days = newIntegerValue
or
IntegerValue = aDateInterval.Days

New in 2019r2

Supported for all project types and targets.

The number of days in the interval.

Sample Code

Var d1 As New Date(2017, 5, 1, TimeZone.Current)
Var d2 As New Date(2017, 5, 20, TimeZone.Current)
Var interval As DateInterval
interval = d2 - d1
// interval.Days = 19