Note: Beginning with Origin 2019, there are three date-time systems in Origin. The default system remains the long-time, adjusted Julian Date system as explained in Dates and Times in Origin. The examples in the table below assume the long-time, default date-time system and when you see "Julian-date value", this refers to Origin's adjusted date value. These functions should work with the alternate systems ...
date2str(today(), "MM/dd/yyyy")$ = 09/27/2018 // default date-time system
date2str(today(), "MM/dd/yyyy")$ = 09/27/2018 // "2018" system, @DSP=2018
... but keep in mind that the numeric values that equate to a given calendar date will differ between systems:
date(9/27/2018) = 2458388 // default date-time system
date(9/27/2018) = 269 // "2018" system, @DSP=2018
For information on Origin's alternate date-time schemes, see Alternate Date-Time Systems in Origin.