¿Cómo calculo la edad de alguien en C #?

Dado un DateTime representa el cumpleaños de una persona, ¿cómo puedo calcular su edad en años?

Una solución fácil de entender y simple.

 // Save today's date. var today = DateTime.Today; // Calculate the age. var age = today.Year - birthdate.Year; // Go back to the year the person was born in case of a leap year if (birthdate > today.AddYears(-age)) age--; 

Sin embargo, esto supone que está buscando la idea occidental de la edad y no está utilizando el cálculo del este asiático .

Esta es una forma extraña de hacerlo, pero si le da formato a la fecha yyyymmdd y resta la fecha de nacimiento de la fecha actual, entonces suelte los últimos 4 dígitos que tiene la edad 🙂

No sé C #, pero creo que esto funcionará en cualquier idioma.

 20080814 - 19800703 = 280111 

Suelta los últimos 4 dígitos = 28 .

C # Code:

 int now = int.Parse(DateTime.Now.ToString("yyyyMMdd")); int dob = int.Parse(dateOfBirth.ToString("yyyyMMdd")); int age = (now - dob) / 10000; 

O alternativamente sin toda la conversión de tipo en la forma de un método de extensión. Error al verificar omitido:

 public static Int32 GetAge(this DateTime dateOfBirth) { var today = DateTime.Today; var a = (today.Year * 100 + today.Month) * 100 + today.Day; var b = (dateOfBirth.Year * 100 + dateOfBirth.Month) * 100 + dateOfBirth.Day; return (a - b) / 10000; } 

No sé cómo se puede aceptar la solución incorrecta. El fragmento de C # correcto fue escrito por Michael Stum

Aquí hay un fragmento de prueba:

 DateTime bDay = new DateTime(2000, 2, 29); DateTime now = new DateTime(2009, 2, 28); MessageBox.Show(string.Format("Test {0} {1} {2}", CalculateAgeWrong1(bDay, now), // outputs 9 CalculateAgeWrong2(bDay, now), // outputs 9 CalculateAgeCorrect(bDay, now))); // outputs 8 

Aquí tienes los métodos:

 public int CalculateAgeWrong1(DateTime birthDate, DateTime now) { return new DateTime(now.Subtract(birthDate).Ticks).Year - 1; } public int CalculateAgeWrong2(DateTime birthDate, DateTime now) { int age = now.Year - birthDate.Year; if (now < birthDate.AddYears(age)) age--; return age; } public int CalculateAgeCorrect(DateTime birthDate, DateTime now) { int age = now.Year - birthDate.Year; if (now.Month < birthDate.Month || (now.Month == birthDate.Month && now.Day < birthDate.Day)) age--; return age; } 

No creo que ninguna de las respuestas proporcione culturas que calculen la edad de manera diferente. Ver, por ejemplo, el cálculo de la edad del este asiático versus el de occidente.

Cualquier respuesta real debe incluir localización. El Patrón de Estrategia probablemente estaría en orden en este ejemplo.

La respuesta simple a esto es aplicar AddYears como se muestra a continuación porque este es el único método nativo para agregar años hasta el 29 de febrero de años bisiestos y obtener el resultado correcto del 28 de febrero para los años comunes.

Algunos creen que el 1 de marzo es el cumpleaños de los saltos, pero ni .Net ni ninguna regla oficial respaldan esto, y la lógica común tampoco explica por qué algunos nacidos en febrero deben tener el 75% de sus cumpleaños en otro mes.

Además, un método Age se presta a agregarse como una extensión de DateTime . Con esto puedes obtener la edad de la manera más simple posible:

  1. Artículo de lista

int age = birthDate.Age ();

 public static class DateTimeExtensions { ///  /// Calculates the age in years of the current System.DateTime object today. ///  /// The date of birth /// Age in years today. 0 is returned for a future date of birth. public static int Age(this DateTime birthDate) { return Age(birthDate, DateTime.Today); } ///  /// Calculates the age in years of the current System.DateTime object on a later date. ///  /// The date of birth /// The date on which to calculate the age. /// Age in years on a later day. 0 is returned as minimum. public static int Age(this DateTime birthDate, DateTime laterDate) { int age; age = laterDate.Year - birthDate.Year; if (age > 0) { age -= Convert.ToInt32(laterDate.Date < birthDate.Date.AddYears(age)); } else { age = 0; } return age; } } 

Ahora, ejecuta esta prueba:

 class Program { static void Main(string[] args) { RunTest(); } private static void RunTest() { DateTime birthDate = new DateTime(2000, 2, 28); DateTime laterDate = new DateTime(2011, 2, 27); string iso = "yyyy-MM-dd"; for (int i = 0; i < 3; i++) { for (int j = 0; j < 3; j++) { Console.WriteLine("Birth date: " + birthDate.AddDays(i).ToString(iso) + " Later date: " + laterDate.AddDays(j).ToString(iso) + " Age: " + birthDate.AddDays(i).Age(laterDate.AddDays(j)).ToString()); } } Console.ReadKey(); } } 

El ejemplo de fecha crítica es este:

Fecha de nacimiento: 2000-02-29 Fecha posterior: 2011-02-28 Edad: 11

Salida:

 { Birth date: 2000-02-28 Later date: 2011-02-27 Age: 10 Birth date: 2000-02-28 Later date: 2011-02-28 Age: 11 Birth date: 2000-02-28 Later date: 2011-03-01 Age: 11 Birth date: 2000-02-29 Later date: 2011-02-27 Age: 10 Birth date: 2000-02-29 Later date: 2011-02-28 Age: 11 Birth date: 2000-02-29 Later date: 2011-03-01 Age: 11 Birth date: 2000-03-01 Later date: 2011-02-27 Age: 10 Birth date: 2000-03-01 Later date: 2011-02-28 Age: 10 Birth date: 2000-03-01 Later date: 2011-03-01 Age: 11 } 

Y para la fecha posterior 2012-02-28:

 { Birth date: 2000-02-28 Later date: 2012-02-28 Age: 12 Birth date: 2000-02-28 Later date: 2012-02-29 Age: 12 Birth date: 2000-02-28 Later date: 2012-03-01 Age: 12 Birth date: 2000-02-29 Later date: 2012-02-28 Age: 11 Birth date: 2000-02-29 Later date: 2012-02-29 Age: 12 Birth date: 2000-02-29 Later date: 2012-03-01 Age: 12 Birth date: 2000-03-01 Later date: 2012-02-28 Age: 11 Birth date: 2000-03-01 Later date: 2012-02-29 Age: 11 Birth date: 2000-03-01 Later date: 2012-03-01 Age: 12 } 

Mi sugerencia

 int age = (int) ((DateTime.Now - bday).TotalDays/365.242199); 

Parece que el año está cambiando en la fecha correcta. (Hice la prueba hasta la edad de 107)

Otra función, no por mí, pero que se encuentra en la web y la refinó un poco:

 public static int GetAge(DateTime birthDate) { DateTime n = DateTime.Now; // To avoid a race condition around midnight int age = n.Year - birthDate.Year; if (n.Month < birthDate.Month || (n.Month == birthDate.Month && n.Day < birthDate.Day)) age--; return age; } 

Solo me vienen a la mente dos cosas: ¿qué hay de las personas de países que no usan el calendario gregoriano? DateTime.Now está en la cultura específica del servidor, creo. Tengo absolutamente 0 conocimiento sobre el hecho de trabajar con calendarios asiáticos y no sé si hay una manera fácil de convertir fechas entre calendarios, pero por si acaso te estás preguntando sobre esos chicos chinos del año 4660 🙂

Llego tarde a la fiesta, pero aquí hay una sola frase:

 int age = new DateTime(DateTime.Now.Subtract(birthday).Ticks).Year-1; 

2 Los principales problemas a resolver son:

1. Calcule la edad exacta : en años, meses, días, etc.

2. Calcule la edad generalmente percibida : a las personas generalmente no les importa qué edad tienen exactamente, solo les importa cuándo es su cumpleaños en el año actual.


La solución para 1 es obvio:

 DateTime birth = DateTime.Parse("1.1.2000"); DateTime today = DateTime.Today; //we usually don't care about birth time TimeSpan age = today - birth; //.NET FCL should guarantee this as precise double ageInDays = age.TotalDays; //total number of days ... also precise double daysInYear = 365.2425; //statistical value for 400 years double ageInYears = ageInDays / daysInYear; //can be shifted ... not so precise 

La solución para 2 es la que no es tan precisa para determinar la edad total, pero la gente la percibe como precisa. Las personas también suelen usarlo cuando calculan su edad “manualmente”:

 DateTime birth = DateTime.Parse("1.1.2000"); DateTime today = DateTime.Today; int age = today.Year - birth.Year; //people perceive their age in years if (today.Month < birth.Month || ((today.Month == birth.Month) && (today.Day < birth.Day))) { age--; //birthday in current year not yet reached, we are 1 year younger ;) //+ no birthday for 29.2. guys ... sorry, just wrong date for birth } 

Notas a 2 .:

  • Esta es mi solución preferida
  • No podemos usar DateTime.DayOfYear o TimeSpans, ya que cambian el número de días en los años bisiestos
  • He puesto allí pocas líneas más para la legibilidad

Solo una nota más ... Crearía 2 métodos estáticos sobrecargados, uno para uso universal, segundo para uso amigable:

 public static int GetAge(DateTime bithDay, DateTime today) { //chosen solution method body } public static int GetAge(DateTime birthDay) { return GetAge(birthDay, DateTime.Now); } 

Hace muchos años, para proporcionar un truco de calculadora de edad en mi sitio web, escribí una función para calcular la edad en una fracción. Este es un puerto rápido de esa función para C # (de la versión de PHP ). Me temo que no he podido probar la versión de C #, ¡pero espero que disfrutes de todos modos!

(Es cierto que esto es un poco artificioso a los efectos de mostrar los perfiles de usuario en Stack Overflow, pero tal vez los lectores encuentren algún uso para él. :-))

 double AgeDiff(DateTime date1, DateTime date2) { double years = date2.Year - date1.Year; /* * If date2 and date1 + round(date2 - date1) are on different sides * of 29 February, then our partial year is considered to have 366 * days total, otherwise it's 365. Note that 59 is the day number * of 29 Feb. */ double fraction = 365 + (DateTime.IsLeapYear(date2.Year) && date2.DayOfYear >= 59 && (date1.DayOfYear < 59 || date1.DayOfYear > date2.DayOfYear) ? 1 : 0); /* * The only really nontrivial case is if date1 is in a leap year, * and date2 is not. So let's handle the others first. */ if (DateTime.IsLeapYear(date2.Year) == DateTime.IsLeapYear(date1.Year)) return years + (date2.DayOfYear - date1.DayOfYear) / fraction; /* * If date2 is in a leap year, but date1 is not and is March or * beyond, shift up by a day. */ if (DateTime.IsLeapYear(date2.Year)) { return years + (date2.DayOfYear - date1.DayOfYear - (date1.DayOfYear >= 59 ? 1 : 0)) / fraction; } /* * If date1 is not on 29 February, shift down date1 by a day if * March or later. Proceed normally. */ if (date1.DayOfYear != 59) { return years + (date2.DayOfYear - date1.DayOfYear + (date1.DayOfYear > 59 ? 1 : 0)) / fraction; } /* * Okay, here date1 is on 29 February, and date2 is not on a leap * year. What to do now? On 28 Feb in date2's year, the ``age'' * should be just shy of a whole number, and on 1 Mar should be * just over. Perhaps the easiest way is to a point halfway * between those two: 58.5. */ return years + (date2.DayOfYear - 58.5) / fraction; } 

Esta es la versión que usamos aquí. Funciona, y es bastante simple. Es la misma idea que la de Jeff, pero creo que es un poco más clara porque separa la lógica para restar una, por lo que es un poco más fácil de entender.

 public static int GetAge(this DateTime dateOfBirth, DateTime dateAsAt) { return dateAsAt.Year - dateOfBirth.Year - (dateOfBirth.DayOfYear < dateAsAt.DayOfYear ? 0 : 1); } 

Podría expandir el operador ternario para hacerlo aún más claro, si cree que ese tipo de cosas no está claro.

Obviamente, esto se hace como un método de extensión en DateTime , pero es evidente que puede tomar esa línea de código que hace el trabajo y ponerlo en cualquier lugar. Aquí tenemos otra sobrecarga del método de extensión que pasa en DateTime.Now , solo para completar.

Yo uso esto:

 public static class DateTimeExtensions { public static int Age(this DateTime birthDate) { return Age(birthDate, DateTime.Now); } public static int Age(this DateTime birthDate, DateTime offsetDate) { int result=0; result = offsetDate.Year - birthDate.Year; if (offsetDate.DayOfYear < birthDate.DayOfYear) { result--; } return result; } } 

La mejor manera que conozco debido a los años bisiestos y todo es:

 DateTime birthDate = new DateTime(2000,3,1); int age = (int)Math.Floor((DateTime.Now - birthDate).TotalDays / 365.25D); 

Espero que esto ayude.

Esto le da “más detalles” a esta pregunta. Tal vez esto es lo que estás buscando

 DateTime birth = new DateTime(1974, 8, 29); DateTime today = DateTime.Now; TimeSpan span = today - birth; DateTime age = DateTime.MinValue + span; // Make adjustment due to MinValue equalling 1/1/1 int years = age.Year - 1; int months = age.Month - 1; int days = age.Day - 1; // Print out not only how many years old they are but give months and days as well Console.Write("{0} years, {1} months, {2} days", years, months, days); 

Creé una función definida por el usuario de SQL Server para calcular la edad de alguien, dada su fecha de nacimiento. Esto es útil cuando lo necesita como parte de una consulta:

 using System; using System.Data; using System.Data.Sql; using System.Data.SqlClient; using System.Data.SqlTypes; using Microsoft.SqlServer.Server; public partial class UserDefinedFunctions { [SqlFunction(DataAccess = DataAccessKind.Read)] public static SqlInt32 CalculateAge(string strBirthDate) { DateTime dtBirthDate = new DateTime(); dtBirthDate = Convert.ToDateTime(strBirthDate); DateTime dtToday = DateTime.Now; // get the difference in years int years = dtToday.Year - dtBirthDate.Year; // subtract another year if we're before the // birth day in the current year if (dtToday.Month < dtBirthDate.Month || (dtToday.Month == dtBirthDate.Month && dtToday.Day < dtBirthDate.Day)) years=years-1; int intCustomerAge = years; return intCustomerAge; } }; 

He pasado un tiempo trabajando en esto y se me ocurrió esto para calcular la edad de alguien en años, meses y días. Probé contra el problema del 29 de febrero y saltamos años y parece funcionar, agradecería cualquier comentario:

 public void LoopAge(DateTime myDOB, DateTime FutureDate) { int years = 0; int months = 0; int days = 0; DateTime tmpMyDOB = new DateTime(myDOB.Year, myDOB.Month, 1); DateTime tmpFutureDate = new DateTime(FutureDate.Year, FutureDate.Month, 1); while (tmpMyDOB.AddYears(years).AddMonths(months) < tmpFutureDate) { months++; if (months > 12) { years++; months = months - 12; } } if (FutureDate.Day >= myDOB.Day) { days = days + FutureDate.Day - myDOB.Day; } else { months--; if (months < 0) { years--; months = months + 12; } days += DateTime.DaysInMonth( FutureDate.AddMonths(-1).Year, FutureDate.AddMonths(-1).Month ) + FutureDate.Day - myDOB.Day; } //add an extra day if the dob is a leap day if (DateTime.IsLeapYear(myDOB.Year) && myDOB.Month == 2 && myDOB.Day == 29) { //but only if the future date is less than 1st March if (FutureDate >= new DateTime(FutureDate.Year, 3, 1)) days++; } } 

Manteniéndolo simple (y posiblemente estúpido :)).

 DateTime birth = new DateTime(1975, 09, 27, 01, 00, 00, 00); TimeSpan ts = DateTime.Now - birth; Console.WriteLine("You are approximately " + ts.TotalSeconds.ToString() + " seconds old."); 
 TimeSpan diff = DateTime.Now - birthdayDateTime; string age = String.Format("{0:%y} years, {0:%M} months, {0:%d}, days old", diff); 

No estoy seguro de cómo exactamente te gustaría que te lo devolviera, así que acabo de hacer una cadena legible.

¿Necesitamos considerar a personas que son menores de 1 año? como cultura china, describimos la edad de los bebés pequeños como 2 meses o 4 semanas.

Debajo está mi implementación, no es tan simple como lo que imaginé, especialmente para tratar con fechas como 2/28.

 public static string HowOld(DateTime birthday, DateTime now) { if (now < birthday) throw new ArgumentOutOfRangeException("birthday must be less than now."); TimeSpan diff = now - birthday; int diffDays = (int)diff.TotalDays; if (diffDays > 7)//year, month and week { int age = now.Year - birthday.Year; if (birthday > now.AddYears(-age)) age--; if (age > 0) { return age + (age > 1 ? " years" : " year"); } else {// month and week DateTime d = birthday; int diffMonth = 1; while (d.AddMonths(diffMonth) <= now) { diffMonth++; } age = diffMonth-1; if (age == 1 && d.Day > now.Day) age--; if (age > 0) { return age + (age > 1 ? " months" : " month"); } else { age = diffDays / 7; return age + (age > 1 ? " weeks" : " week"); } } } else if (diffDays > 0) { int age = diffDays; return age + (age > 1 ? " days" : " day"); } else { int age = diffDays; return "just born"; } } 

Esta implementación ha pasado por debajo de los casos de prueba.

 [TestMethod] public void TestAge() { string age = HowOld(new DateTime(2011, 1, 1), new DateTime(2012, 11, 30)); Assert.AreEqual("1 year", age); age = HowOld(new DateTime(2011, 11, 30), new DateTime(2012, 11, 30)); Assert.AreEqual("1 year", age); age = HowOld(new DateTime(2001, 1, 1), new DateTime(2012, 11, 30)); Assert.AreEqual("11 years", age); age = HowOld(new DateTime(2012, 1, 1), new DateTime(2012, 11, 30)); Assert.AreEqual("10 months", age); age = HowOld(new DateTime(2011, 12, 1), new DateTime(2012, 11, 30)); Assert.AreEqual("11 months", age); age = HowOld(new DateTime(2012, 10, 1), new DateTime(2012, 11, 30)); Assert.AreEqual("1 month", age); age = HowOld(new DateTime(2008, 2, 28), new DateTime(2009, 2, 28)); Assert.AreEqual("1 year", age); age = HowOld(new DateTime(2008, 3, 28), new DateTime(2009, 2, 28)); Assert.AreEqual("11 months", age); age = HowOld(new DateTime(2008, 3, 28), new DateTime(2009, 3, 28)); Assert.AreEqual("1 year", age); age = HowOld(new DateTime(2009, 1, 28), new DateTime(2009, 2, 28)); Assert.AreEqual("1 month", age); age = HowOld(new DateTime(2009, 2, 1), new DateTime(2009, 3, 1)); Assert.AreEqual("1 month", age); // NOTE. // new DateTime(2008, 1, 31).AddMonths(1) == new DateTime(2009, 2, 28); // new DateTime(2008, 1, 28).AddMonths(1) == new DateTime(2009, 2, 28); age = HowOld(new DateTime(2009, 1, 31), new DateTime(2009, 2, 28)); Assert.AreEqual("4 weeks", age); age = HowOld(new DateTime(2009, 2, 1), new DateTime(2009, 2, 28)); Assert.AreEqual("3 weeks", age); age = HowOld(new DateTime(2009, 2, 1), new DateTime(2009, 3, 1)); Assert.AreEqual("1 month", age); age = HowOld(new DateTime(2012, 11, 5), new DateTime(2012, 11, 30)); Assert.AreEqual("3 weeks", age); age = HowOld(new DateTime(2012, 11, 1), new DateTime(2012, 11, 30)); Assert.AreEqual("4 weeks", age); age = HowOld(new DateTime(2012, 11, 20), new DateTime(2012, 11, 30)); Assert.AreEqual("1 week", age); age = HowOld(new DateTime(2012, 11, 25), new DateTime(2012, 11, 30)); Assert.AreEqual("5 days", age); age = HowOld(new DateTime(2012, 11, 29), new DateTime(2012, 11, 30)); Assert.AreEqual("1 day", age); age = HowOld(new DateTime(2012, 11, 30), new DateTime(2012, 11, 30)); Assert.AreEqual("just born", age); age = HowOld(new DateTime(2000, 2, 29), new DateTime(2009, 2, 28)); Assert.AreEqual("8 years", age); age = HowOld(new DateTime(2000, 2, 29), new DateTime(2009, 3, 1)); Assert.AreEqual("9 years", age); Exception e = null; try { age = HowOld(new DateTime(2012, 12, 1), new DateTime(2012, 11, 30)); } catch (ArgumentOutOfRangeException ex) { e = ex; } Assert.IsTrue(e != null); } 

Espero que sea útil.

Aquí hay otra respuesta:

 public static int AgeInYears(DateTime birthday, DateTime today) { return ((today.Year - birthday.Year) * 372 + (today.Month - birthday.Month) * 31 + (today.Day - birthday.Day)) / 372; } 

Esto ha sido ampliamente probado en unidades. Se ve un poco “mágico”. El número 372 es la cantidad de días que habría en un año si cada mes tuviera 31 días.

La explicación de por qué funciona ( levantado de aquí ) es:

Vamos a establecer Yn = DateTime.Now.Year, Yb = birthday.Year, Mn = DateTime.Now.Month, Mb = birthday.Month, Dn = DateTime.Now.Day, Db = birthday.Day

age = Yn - Yb + (31*(Mn - Mb) + (Dn - Db)) / 372

Sabemos que lo que necesitamos es Yn-Yb si ya se ha alcanzado la fecha, Yn-Yb-1 si no lo ha hecho.

a) Si Mn , tenemos -341 <= 31*(Mn-Mb) <= -31 and -30 <= Dn-Db <= 30

-371 <= 31*(Mn - Mb) + (Dn - Db) <= -1

Con división entera

(31*(Mn - Mb) + (Dn - Db)) / 372 = -1

b) Si Mn=Mb y Dn , tenemos 31*(Mn - Mb) = 0 and -30 <= Dn-Db <= -1

Con división entera, otra vez

(31*(Mn - Mb) + (Dn - Db)) / 372 = -1

c) Si Mn>Mb , tenemos 31 <= 31*(Mn-Mb) <= 341 and -30 <= Dn-Db <= 30

1 <= 31*(Mn - Mb) + (Dn - Db) <= 371

Con división entera

(31*(Mn - Mb) + (Dn - Db)) / 372 = 0

d) Si Mn=Mb y Dn>Db , tenemos 31*(Mn - Mb) = 0 and 1 <= Dn-Db <= 3 0

Con división entera, otra vez

(31*(Mn - Mb) + (Dn - Db)) / 372 = 0

e) If Mn=Mb and Dn=Db , we have 31*(Mn - Mb) + Dn-Db = 0

and therefore (31*(Mn - Mb) + (Dn - Db)) / 372 = 0

The simplest way I’ve ever found is this. It works correctly for the US and western europe locales. Can’t speak to other locales, especially places like China. 4 extra compares, at most, following the initial computation of age.

 public int AgeInYears(DateTime birthDate, DateTime referenceDate) { Debug.Assert(referenceDate >= birthDate, "birth date must be on or prior to the reference date"); DateTime birth = birthDate.Date; DateTime reference = referenceDate.Date; int years = (reference.Year - birth.Year); // // an offset of -1 is applied if the birth date has // not yet occurred in the current year. // if (reference.Month > birth.Month); else if (reference.Month < birth.Month) --years; else // in birth month { if (reference.Day < birth.Day) --years; } return years ; } 

I was looking over the answers to this and noticed that nobody has made reference to regulatory/legal implications of leap day births. For instance, per Wikipedia , if you're born on February 29th in various jurisdictions, you're non-leap year birthday varies:

  • In the United Kingdom and Hong Kong: it's the ordinal day of the year, so the next day, March 1st is your birthday.
  • In New Zealand: it's the previous day, February 28th for the purposes of driver licencing, and March 1st for other purposes.
  • Taiwan: it's February 28th.

And as near as I can tell, in the US, the statutes are silent on the matter, leaving it up to the common law and to how various regulatory bodies define things in their regulations.

To that end, an improvement:

 public enum LeapDayRule { OrdinalDay = 1 , LastDayOfMonth = 2 , } static int ComputeAgeInYears(DateTime birth, DateTime reference, LeapYearBirthdayRule ruleInEffect) { bool isLeapYearBirthday = CultureInfo.CurrentCulture.Calendar.IsLeapDay(birth.Year, birth.Month, birth.Day); DateTime cutoff; if (isLeapYearBirthday && !DateTime.IsLeapYear(reference.Year)) { switch (ruleInEffect) { case LeapDayRule.OrdinalDay: cutoff = new DateTime(reference.Year, 1, 1) .AddDays(birth.DayOfYear - 1); break; case LeapDayRule.LastDayOfMonth: cutoff = new DateTime(reference.Year, birth.Month, 1) .AddMonths(1) .AddDays(-1); break; default: throw new InvalidOperationException(); } } else { cutoff = new DateTime(reference.Year, birth.Month, birth.Day); } int age = (reference.Year - birth.Year) + (reference >= cutoff ? 0 : -1); return age < 0 ? 0 : age; } 

It should be noted that this code assumes:

  • A western (European) reckoning of age, and
  • A calendar, like the Gregorian calendar that inserts a single leap day at the end of a month.

This is one of the most accurate answer that is able to resolve the birthday of 29th of Feb compare to any year of 28th Feb.

 public int GetAge(DateTime birthDate) { int age = DateTime.Now.Year - birthDate.Year; if (birthDate.DayOfYear > DateTime.Now.DayOfYear) age--; return age; } 

Here is a solution.

 DateTime dateOfBirth = new DateTime(2000, 4, 18); DateTime currentDate = DateTime.Now; int ageInYears = 0; int ageInMonths = 0; int ageInDays = 0; ageInDays = currentDate.Day - dateOfBirth.Day; ageInMonths = currentDate.Month - dateOfBirth.Month; ageInYears = currentDate.Year - dateOfBirth.Year; if (ageInDays < 0) { ageInDays += DateTime.DaysInMonth(currentDate.Year, currentDate.Month); ageInMonths = ageInMonths--; if (ageInMonths < 0) { ageInMonths += 12; ageInYears--; } } if (ageInMonths < 0) { ageInMonths += 12; ageInYears--; } Console.WriteLine("{0}, {1}, {2}", ageInYears, ageInMonths, ageInDays); 

This is not a direct answer, but more of a philosophical reasoning about the problem at hand from a quasi-scientific point of view.

I would argue that the question does not specify the unit nor culture in which to measure age, most answers seem to assume an integer annual representation. The SI-unit for time is second , ergo the correct generic answer should be (of course assuming normalized DateTime and taking no regard whatsoever to relativistic effects):

 var lifeInSeconds = (DateTime.Now.Ticks - then.Ticks)/TickFactor; 

In the Christian way of calculating age in years:

 var then = ... // Then, in this case the birthday var now = DateTime.UtcNow; int age = now.Year - then.Year; if (now.AddYears(-age) < then) age--; 

In finance there is a similar problem when calculating something often referred to as the Day Count Fraction , which roughly is a number of years for a given period. And the age issue is really a time measuring issue.

Example for the actual/actual (counting all days "correctly") convention:

 DateTime start, end = .... // Whatever, assume start is before end double startYearContribution = 1 - (double) start.DayOfYear / (double) (DateTime.IsLeapYear(start.Year) ? 366 : 365); double endYearContribution = (double)end.DayOfYear / (double)(DateTime.IsLeapYear(end.Year) ? 366 : 365); double middleContribution = (double) (end.Year - start.Year - 1); double DCF = startYearContribution + endYearContribution + middleContribution; 

Another quite common way to measure time generally is by "serializing" (the dude who named this date convention must seriously have been trippin'):

 DateTime start, end = .... // Whatever, assume start is before end int days = (end - start).Days; 

I wonder how long we have to go before a relativistic age in seconds becomes more useful than the rough approximation of earth-around-sun-cycles during one's lifetime so far 🙂 Or in other words, when a period must be given a location or a function representing motion for itself to be valid 🙂

How about this solution?

 static string CalcAge(DateTime birthDay) { DateTime currentDate = DateTime.Now; int approximateAge = currentDate.Year - birthDay.Year; int daysToNextBirthDay = (birthDay.Month * 30 + birthDay.Day) - (currentDate.Month * 30 + currentDate.Day) ; if (approximateAge == 0 || approximateAge == 1) { int month = Math.Abs(daysToNextBirthDay / 30); int days = Math.Abs(daysToNextBirthDay % 30); if (month == 0) return "Your age is: " + daysToNextBirthDay + " days"; return "Your age is: " + month + " months and " + days + " days"; ; } if (daysToNextBirthDay > 0) return "Your age is: " + --approximateAge + " Years"; return "Your age is: " + approximateAge + " Years"; ; } 

I have a customized method to calculate age, plus a bonus validation message just in case it helps:

 public void GetAge(DateTime dob, DateTime now, out int years, out int months, out int days) { years = 0; months = 0; days = 0; DateTime tmpdob = new DateTime(dob.Year, dob.Month, 1); DateTime tmpnow = new DateTime(now.Year, now.Month, 1); while (tmpdob.AddYears(years).AddMonths(months) < tmpnow) { months++; if (months > 12) { years++; months = months - 12; } } if (now.Day >= dob.Day) days = days + now.Day - dob.Day; else { months--; if (months < 0) { years--; months = months + 12; } days += DateTime.DaysInMonth(now.AddMonths(-1).Year, now.AddMonths(-1).Month) + now.Day - dob.Day; } if (DateTime.IsLeapYear(dob.Year) && dob.Month == 2 && dob.Day == 29 && now >= new DateTime(now.Year, 3, 1)) days++; } private string ValidateDate(DateTime dob) //This method will validate the date { int Years = 0; int Months = 0; int Days = 0; GetAge(dob, DateTime.Now, out Years, out Months, out Days); if (Years < 18) message = Years + " is too young. Please try again on your 18th birthday."; else if (Years >= 65) message = Years + " is too old. Date of Birth must not be 65 or older."; else return null; //Denotes validation passed } 

Method call here and pass out datetime value (MM/dd/yyyy if server set to USA locale). Replace this with anything a messagebox or any container to display:

 DateTime dob = DateTime.Parse("03/10/1982"); string message = ValidateDate(dob); lbldatemessage.Visible = !StringIsNullOrWhitespace(message); lbldatemessage.Text = message ?? ""; //Ternary if message is null then default to empty string 

Remember you can format the message any way you like.

 private int GetAge(int _year, int _month, int _day { DateTime yourBirthDate= new DateTime(_year, _month, _day); DateTime todaysDateTime = DateTime.Today; int noOfYears = todaysDateTime.Year - yourBirthDate.Year; if (DateTime.Now.Month < yourBirthDate.Month || (DateTime.Now.Month == yourBirthDate.Month && DateTime.Now.Day < yourBirthDate.Day)) { noOfYears--; } return noOfYears; } 

I used ScArcher2’s solution for an accurate Year calculation of a persons age but I needed to take it further and calculate their Months and Days along with the Years.

  public static Dictionary CurrentAgeInYearsMonthsDays(DateTime? ndtBirthDate, DateTime? ndtReferralDate) { //---------------------------------------------------------------------- // Can't determine age if we don't have a dates. //---------------------------------------------------------------------- if (ndtBirthDate == null) return null; if (ndtReferralDate == null) return null; DateTime dtBirthDate = Convert.ToDateTime(ndtBirthDate); DateTime dtReferralDate = Convert.ToDateTime(ndtReferralDate); //---------------------------------------------------------------------- // Create our Variables //---------------------------------------------------------------------- Dictionary dYMD = new Dictionary(); int iNowDate, iBirthDate, iYears, iMonths, iDays; string sDif = ""; //---------------------------------------------------------------------- // Store off current date/time and DOB into local variables //---------------------------------------------------------------------- iNowDate = int.Parse(dtReferralDate.ToString("yyyyMMdd")); iBirthDate = int.Parse(dtBirthDate.ToString("yyyyMMdd")); //---------------------------------------------------------------------- // Calculate Years //---------------------------------------------------------------------- sDif = (iNowDate - iBirthDate).ToString(); iYears = int.Parse(sDif.Substring(0, sDif.Length - 4)); //---------------------------------------------------------------------- // Store Years in Return Value //---------------------------------------------------------------------- dYMD.Add("Years", iYears); //---------------------------------------------------------------------- // Calculate Months //---------------------------------------------------------------------- if (dtBirthDate.Month > dtReferralDate.Month) iMonths = 12 - dtBirthDate.Month + dtReferralDate.Month - 1; else iMonths = dtBirthDate.Month - dtReferralDate.Month; //---------------------------------------------------------------------- // Store Months in Return Value //---------------------------------------------------------------------- dYMD.Add("Months", iMonths); //---------------------------------------------------------------------- // Calculate Remaining Days //---------------------------------------------------------------------- if (dtBirthDate.Day > dtReferralDate.Day) //Logic: Figure out the days in month previous to the current month, or the admitted month. // Subtract the birthday from the total days which will give us how many days the person has lived since their birthdate day the previous month. // then take the referral date and simply add the number of days the person has lived this month. //If referral date is january, we need to go back to the following year's December to get the days in that month. if (dtReferralDate.Month == 1) iDays = DateTime.DaysInMonth(dtReferralDate.Year - 1, 12) - dtBirthDate.Day + dtReferralDate.Day; else iDays = DateTime.DaysInMonth(dtReferralDate.Year, dtReferralDate.Month - 1) - dtBirthDate.Day + dtReferralDate.Day; else iDays = dtReferralDate.Day - dtBirthDate.Day; //---------------------------------------------------------------------- // Store Days in Return Value //---------------------------------------------------------------------- dYMD.Add("Days", iDays); return dYMD; } 

SQL version:

 declare @dd smalldatetime = '1980-04-01' declare @age int = YEAR(GETDATE())-YEAR(@dd) if (@dd> DATEADD(YYYY, -@age, GETDATE())) set @age = @age -1 print @age 

I’ve made one small change to Mark Soen’s answer: I’ve rewriten the third line so that the expression can be parsed a bit more easily.

 public int AgeInYears(DateTime bday) { DateTime now = DateTime.Today; int age = now.Year - bday.Year; if (bday.AddYears(age) > now) age--; return age; } 

I’ve also made it into a function for the sake of clarity.