Date.diff

You're seeing just the function diff, go back to Date module for more information.
Link to this function

diff(date1, date2)

View Source (since 1.5.0)

Specs

Calculates the difference between two dates, in a full number of days.

It returns the number of Gregorian days between the dates. Only Date structs that follow the same or compatible calendars can be compared this way. If two calendars are not compatible, it will raise.

Examples

iex> Date.diff(~D[2000-01-03], ~D[2000-01-01])
2
iex> Date.diff(~D[2000-01-01], ~D[2000-01-03])
-2
iex> Date.diff(~D[0000-01-02], ~D[-0001-12-30])
3
iex> Date.diff(~D[2000-01-01], ~N[2000-01-03 09:00:00])
-2