How do I calculate relative time?

Question :
Given a specific DateTime value, how do I display relative time, like:

• 2 hours ago
• 3 days ago
• a month ago

Answer :

Jeff, your code is nice but could be clearer with constants (as suggested in Code Complete). const int SECOND = 1; const int MINUTE = 60 * SECOND; const int HOUR = 60 * MINUTE; const int DAY = 24 * HOUR; const int MONTH = 30 * DAY; var ts = new TimeSpan(DateTime.UtcNow.Ticks - yourDate.Ticks); double delta = Math.Abs(ts.TotalSeconds); if (delta < 1 * MINUTE) { return ts.Seconds == 1 ? "one second ago" : ts.Seconds + " seconds ago"; } if (delta < 2 * MINUTE) { return "a minute ago"; } if (delta < 45 * MINUTE) { return ts.Minutes + " minutes ago"; } if (delta < 90 * MINUTE) { return "an hour ago"; } if (delta < 24 * HOUR) { return ts.Hours + " hours ago"; } if (delta < 48 * HOUR) { return "yesterday"; } if (delta < 30 * DAY) { return ts.Days + " days ago"; } if (delta < 12 * MONTH) { int months = Convert.ToInt32(Math.Floor((double)ts.Days / 30)); return months <= 1 ? "one month ago" : months + " months ago"; } else { int years = Convert.ToInt32(Math.Floor((double)ts.Days / 365)); return years <= 1 ? "one year ago" : years + " years ago"; }