Posted on Sep 29, 2022 • Originally published at rmauro.dev on Sep 29, 2022

Calculate Time Ago with C#

Here is a small extension method over System.DateTime that gives its relative time readable for humans, such as:

one minute ago
2 minutes ago
one hour ago
3 hours ago
3 days ago

Check out this extension method over the DateTime structure using switch patterns.

public static string AsTimeAgo(this DateTime dateTime) { TimeSpan timeSpan = DateTime.Now.Subtract(dateTime); return timeSpan.TotalSeconds switch { <= 60 => $"{timeSpan.Seconds} seconds ago", _ => timeSpan.TotalMinutes switch { <= 1 => "about a minute ago", < 60 => $"about {timeSpan.Minutes} minutes ago", _ => timeSpan.TotalHours switch { <= 1 => "about an hour ago", < 24 => $"about {timeSpan.Hours} hours ago", _ => timeSpan.TotalDays switch { <= 1 => "yesterday", <= 30 => $"about {timeSpan.Days} days ago", <= 60 => "about a month ago", < 365 => $"about {timeSpan.Days / 30} months ago", <= 365 * 2 => "about a year ago", _ => $"about {timeSpan.Days / 365} years ago" } } } }; }

Extension method AsTimeAgo

Bonus! Different solutions for the same problem

Surfing the web - I'm so old - I found two more solutions for the same problem.

Tell me in the comments section which one you like the best.

First Solution

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"; }

Found on https://stackoverflow.com/questions/11/calculate-relative-time-in-c-sharp

Second Solution

public static string TimeAgo(this DateTime dateTime) { string result = string.Empty; var timeSpan = DateTime.Now.Subtract(dateTime); if (timeSpan <= TimeSpan.FromSeconds(60)) { result = string.Format("{0} seconds ago", timeSpan.Seconds); } else if (timeSpan <= TimeSpan.FromMinutes(60)) { result = timeSpan.Minutes > 1 ? String.Format("about {0} minutes ago", timeSpan.Minutes) : "about a minute ago"; } else if (timeSpan <= TimeSpan.FromHours(24)) { result = timeSpan.Hours > 1 ? String.Format("about {0} hours ago", timeSpan.Hours) : "about an hour ago"; } else if (timeSpan <= TimeSpan.FromDays(30)) { result = timeSpan.Days > 1 ? String.Format("about {0} days ago", timeSpan.Days) : "yesterday"; } else if (timeSpan <= TimeSpan.FromDays(365)) { result = timeSpan.Days > 30 ? String.Format("about {0} months ago", timeSpan.Days / 30) : "about a month ago"; } else { result = timeSpan.Days > 365 ? String.Format("about {0} years ago", timeSpan.Days / 365) : "about a year ago"; } return result; }