Calculate Last Day of the Next Month

Question

I am attempting to use the DateTime function in C# to calculate the last day of next month.

For example, today is December 17th 2015. I want the DateTime function to return January 31st 2016 (the last day of next month).

I am using the following to calculate the first day of next month (this works):

DateTime firstDayNextMonth = DateTime.Today.AddDays(-DateTime.Now.Day+1).AddMonths(1);

Answer 1

DateTime reference = DateTime.Now;
DateTime firstDayThisMonth = new DateTime(reference.Year, reference.Month, 1);
DateTime firstDayPlusTwoMonths = firstDayThisMonth.AddMonths(2);
DateTime lastDayNextMonth = firstDayPlusTwoMonths.AddDays(-1);
DateTime endOfLastDayNextMonth = firstDayPlusTwoMonths.AddTicks(-1);

Demo: http://rextester.com/AKDI52378