Compare two date ranges to see if they overlap. This is the source code for a Youtube video to be published at http://www.youtube.com/user/CodingForTheWin

gistfile1.txt

using System;

namespace Power
{
    class Program
    {
        static void Main(string[] args)
        {
            var a = new DateRange { Start = new DateTime(2014, 01, 10), End = new DateTime(2014, 01, 20) };
            
            var b = new DateRange[] { 
                 new DateRange {Start = new DateTime(2014, 01, 01), End = new DateTime(2014, 01, 02) }  // 1
                ,new DateRange {Start = new DateTime(2014, 01, 05), End = new DateTime(2014, 01, 15) }  // 2
                ,new DateRange {Start = new DateTime(2014, 01, 05), End = new DateTime(2014, 01, 10) }  // 3
                ,new DateRange {Start = new DateTime(2014, 01, 10), End = new DateTime(2014, 01, 15) }  // 4
                ,new DateRange {Start = new DateTime(2014, 01, 15), End = new DateTime(2014, 01, 16) }  // 5
                ,new DateRange {Start = new DateTime(2014, 01, 15), End = new DateTime(2014, 01, 20) }  // 6
                ,new DateRange {Start = new DateTime(2014, 01, 10), End = new DateTime(2014, 01, 20) }  // 7
                ,new DateRange {Start = new DateTime(2014, 01, 15), End = new DateTime(2014, 01, 25) }  // 8
                ,new DateRange {Start = new DateTime(2014, 01, 20), End = new DateTime(2014, 01, 25) }  // 9
                ,new DateRange {Start = new DateTime(2014, 01, 22), End = new DateTime(2014, 01, 25) }  // 10
                ,new DateRange {Start = new DateTime(2014, 01, 10), End = new DateTime(2014, 01, 25) }  // 11
                ,new DateRange {Start = new DateTime(2014, 01, 05), End = new DateTime(2014, 01, 20) }  // 12
                ,new DateRange {Start = new DateTime(2014, 01, 05), End = new DateTime(2014, 01, 25) }  // 13
            };

            foreach (var d in b)
            {
                Console.WriteLine(string.Format("{0:yyyy-MM-dd}---{1:yyyy-MM-dd} {2} {3:yyyy-MM-dd}---{4:yyyy-MM-dd}", 
                    a.Start, 
                    a.End, 
                    dateRangesOverlap(a, d) ? "overlaps": "does not overlap",
                    d.Start,
                    d.End));
            }
            Console.ReadLine();

        }

        public class DateRange
        {
            public DateTime Start {get;set;}
            public DateTime End {get;set;}
        }

        private static bool dateRangesOverlap(DateRange a, DateRange b)
        {
            return !((b.End < a.Start) || (b.Start > a.End));
        }
    }
}