Calculate the no of days in the Present Month

Hi All,

I am working on a report and I need to find the no of days in the month according to the date entered by the user.

I am using User Response function to get the date.

Eg:

  if user has entered the date as 4th March 2016 then it means that month is march ,so I want no of days in month as 31(March has 31 days ).  Similarly, for April it should come as 30 days.

Please help.I need this formula.