Date calculations

Background info
GuiXT uses the following rules for handling dates in computations, or comparisons with < or >:

(1) Strings in the formats d.m.y, m/d/y, m-d-y, y.m.d, y/m/d, y-m-d are considered to be dates

(2) A date in one of these date formats is automatically converted to an absolute number of days, before the calculation or comparison is carried out

(3) If one adds or subtracts a number to/from a date, the result is formatted as a date again, using the same date format as the given date
Example 1

Set V[mydate1] "01.01.2018"
Set V[mydate2]

Set V[diff]   "&V[mydate2]" - "&V[mydate1]"

Message "There are &V[diff] days between &V[mydate1] and &V[mydate2]"

Sample message 1

Example 2

Set V[mydate1] "12/06/2018"
Set V[mydate2] "&V[mydate1]" + 1

Message "&V[mydate1] is followed by &V[mydate2]"

Sample message 2