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Creating and using Constructors in C# along with Boolean methods

I am having some trouble with constructors in a C# assignment. The first block of code below contains some of the instructions for the assignment. Essentially, as I understand it, I am to create two constructors, one for setting a default date, and another for checking a date from the user. Also, there is a SetDate method that seems to be doing the same thing. These seem redundant, yet according to the assignment instructions, both are required. I am VERY new to object-oriented programming so I am not sure how to "pass" stuff to a constructor or really how to use it and call it in the main method. The second block of code is what I have written so far. All of the date validation methods seem fine. But, I have no idea what to do with the public Date(int M, int D, int Y) constructor and the SetDate method. What should each of these be doing? Also, why am I being instructed to use integer variables M, D, Y when I am also being told to declare Month, Day, and Year above? Any insight that might aid me in understanding how to use this Constructer and how it relates and differs in function from the SetDate method would be greatly appreciated.
//Create a Date Class
//This class holds:
private int Month;
private int Day;
private int Year;
//Include the following constructors/methods. Include others/more if you
//need them.
// Sets date to 1/1/1900
public Date()
// Sets date to user’s input.
// Checks to see the date is valid
// If it isn’t valid, print message and set date to 1/1/1900
public Date(int M, int D, int Y)
// Sets date to user’s input.
// Checks to see the date is valid
// If it isn’t valid, print message and set date to 1/1/1900
public Boolean SetDate(int M, int D, int Y)ere
//******************************************************************************
class Date
{
private int Month;
private int Day;
private int Year;
// Sets date to 1/1/1900
public Date()
{
Month = 1;
Day = 1;
Year = 1900;
}
public Date(int M, int D, int Y)
{
Month = M;
Day = D;
Year = Y;
}
public Boolean SetDate(int M, int D, int Y)
{
int valDate = 0;
Console.WriteLine("You will be prompted to enter three(3) numbers to represent a month, " +
"day, and year. Only dates between 1/1/1900 and 12/31/2100 are valid.");
Console.WriteLine("");
while (valDate < 1)
{
Console.WriteLine("Enter the number for the month.");
M = int.Parse(Console.ReadLine());
Console.WriteLine("");
Console.WriteLine("Enter the number for the day.");
D = int.Parse(Console.ReadLine());
Console.WriteLine("");
Console.WriteLine("Enter the number for the year.");
Y = int.Parse(Console.ReadLine());
Console.WriteLine("");
ValidateDate();
if (ValidateDate())
{
DisplayDate();
valDate++;
return true;
}
else
{
Console.WriteLine("Please enter a valid date.");
Console.WriteLine("");
Month = 1;
Day = 1;
Year = 1900;
return false;
}
}
return false;
}
// Determines if date is valid.
public Boolean ValidateDate()
{
ValidateMonth();
ValidateDay();
ValidateYear();
if (ValidateMonth() && ValidateDay() && ValidateYear())
{
return true;
}
else
{
return false;
}
}
// Determines if month is valid.
public Boolean ValidateMonth()
{
if (Month >= 1 && Month <= 12)
{
return true;
}
else
{
return false;
}
}
// Determines if year is valid.
public Boolean ValidateYear()
{
if(Year >= 1900 && Year <= 2100)
{
return true;
}
else
{
return false;
}
}
// Determines if day is valid
public Boolean ValidateDay()
{
IsLeapYear();
if(Month == 1 || Month == 3 || Month == 5 || Month == 7 || Month == 8 || Month == 10 || Month == 12)
{
if (Day >= 1 && Day <= 31)
{
return true;
}
else
{
return false;
}
}
else if (Month == 4 || Month == 6 || Month == 9 || Month == 11)
{
if (Day >= 1 && Day <= 30)
{
return true;
}
else
{
return false;
}
}
else if (Month == 2 && IsLeapYear())
{
if (Day >= 1 && Day <= 29)
{
return true;
}
else
{
return false;
}
}
else if (Month == 2 && !IsLeapYear())
{
if (Day >= 1 && Day <= 28)
{
return true;
}
else
{
return false;
}
}
else
{
return false;
}
}
// Determine if year is a leap year
public Boolean IsLeapYear()
{
if ((Year % 4 == 0 && Year % 100 != 0) || (Year % 400 == 0))
{
return true;
}
else
{
return false;
}
}
// Print date to screen in format M/D/Y
public void DisplayDate()
{
Console.WriteLine(ShowDate());
}
public String ShowDate()
{
StringBuilder myStringBuilder = new StringBuilder();
myStringBuilder.AppendFormat("{0} / {1} / {2}", Month, Day, Year);
return (myStringBuilder.ToString());
}
static void Main(string[] args)
{
Date NewDate = new Date();
NewDate.Date();
Console.ReadLine();
}
}

It looks like you've been asked to create a method and a constructor that are doing the same thing. The simple thing to do in this case is to have the constructor call the method.
The only comment I would make about your code is that the problem statement you showed did not require the input to be gathered in the SetDate method. Given the statement it seems like the input from the user would be gathered outside your class.
I don't know what your requirements are for the failure message. That might make sense in it's own method as well.
Here is an example:
public class Date
{
private int Month;
private int Day;
private int Year;
public Date()
{
SetDefaultDate();
}
public Date(int M, int D, int Y)
{
SetDate(M, D, Y);
}
public void SetDate(int M, int D, int Y)
{
if (IsValidDate(M, D, Y))
{
Month = M;
Day = D;
Year = Y;
}
else
{
SetDefaultDate();
}
}
private bool IsValidDate(int M, int D, int Y)
{
// validation logic.. return true if all parameters result in valid date
// false if they do not. If it is an invalid date print the failure message.
return true;
}
private void SetDefaultDate()
{
Month = 1;
Day = 1;
Year = 1900;
}
}

If you want to make some real application using date then i'd suggesting taking look at the DateTime struct in System namespace. That has TryParse function which will return you true or false whether if the input was valid or not.
However it seems like you're doing some programming exercise so in that case my answer would be: It's not very good to have arguments in constructor which could lead to an invalid object - in your case invalid date. That's because once calling the constructor you will have an object in one way or another, except if you throw exception in constructor. Yet if you still want to have it like that then you need to have a property or public variable called "IsValid" in the class/struct which tells if valid date was given with constructor.
Nicer option is follow the DateTime approach - have a public static function which return valid Date object. Like this:
public bool TryParse(int m, int d, int y, out Date date)
{
// validate
// if valid then return Date object like that:
date = new Date()
{
Month = m,
Day = d,
Year = y
};
return true;
// Or like that:
date = new Date(m, d, y);
return true;
// if not valid then return null (because have to return something)
date = null;
return false;
}

Compare Date is Greater than in C#

I'm trying to check if the passing variable date is greater than a static date which I have included in the code and currently trying to use the following code,
private String LastPayDate {
get {
string foo;
if(Parameters.TryGetValue("Last Pay Date", out foo))
return foo;
else
return null;
}
}
private Boolean IsLastPay() {
if (!string.IsNullOrEmpty(LastPayDate)) {
if(DateTime.Parse(Parameters.TryGetValue("Last Pay Date") >="24/05/2018")
return true;
else
return false;
}
return false;
}
however the only error I get is within below code section,
if(DateTime.Parse(Parameters.TryGetValue("Last Pay Date") > "24/05/2018")
can anyone help please ?

If you want to compare DateTimes, compare them, but not strings:
//TODO: what is the magic number (date) 24 May 2018?
private Boolean IsLastPay() {
if (Parameters.TryGetValue("Last Pay Date", out var dateSt))
if (DateTime.TryParse(dateSt, out var paramDate))
return paramDate >= new DateTime(2018, 5, 24);
else
return false; // DateTime.TryParse failed to parse the parameter
else
return false; // Parameters.TryGetValue failed to get the value
}

Thank you for respond. It did helped and I've managed to use below code and its working now, Much appreciate Help!
private Boolean IsLastPay()
{
if (!string.IsNullOrEmpty(LastPayDate))
{
string lpd;
}
if(Parameters.TryGetValue("Last Pay Date", out lpd))
{
if(DateTime.Parse(lpd) > new DateTime(2018,05,24))
return true;
else
return false;
}
}
return false;
}

Why not use the DateTime.Compare() method of DateTime class.
For this you need to have both the variables/objects of type DateTime.
string staticDate = "24/05/2018"; //dd-MM-yyyy
string inputDate = "14/08/20"; //dd-MM-yy
string greaterDate = CalculateGreaterDate(inputDate, staticDate); // 14/08/20 is greater
public static string CalculateGreaterDate(string iDate, string sDate)
{
// input date
string input = iDate;
var inputElements = input.Split('/');
int inputDay = Convert.ToInt32(inputElements[0]); //14
int inputMonth = Convert.ToInt32(inputElements[1]); //08
int inputYear = Convert.ToInt32(inputElements[2]); //20
// static date
string static = sDate;
var staticElements = static.Split('/');
int staticDay = Convert.ToInt32(staticElements[0]); //24
int staticMonth = Convert.ToInt32(staticElements[1]); //05
int staticYear = Convert.ToInt32(staticElements[2]); //2018
DateTime inputDate = new DateTime(inputYear, inputMonth, inputDay);
DateTime staticDate = new DateTime(staticYear, staticMonth, staticDay);
// DateTime.Compare(d1, d2) returns:
// > 0 : d1 is greater than d2
// = 0 : d1 & d2 are equal
// < 0 : d1 is smaller than d2
int result = DateTime.Compare(inputDate, staticDate);
if (result > 0)
return iDate + " is greater";
else if (result < 0)
return sDate + " is greater";
else if (result == 0)
return iDate + " is equal to " + sDate;
}

Regex c# - where to insert the blank space

I want to allow the user to enter the year in blank but I don´t know where to put \s\s\s\s in the following expression.
Here is an example of what I need to do: if the user inserts 03-07-_____ the program must be executed every 3Th of July of each year(and it proceeds the same way if the user inserts blank date, month or year or twoo of this three)
System.Text.RegularExpressions.Regex rdate =
new System.Text.RegularExpressions.Regex(#"^((((0?[1-9]|[12]\d|3[01]|\s\s|\s\d)[\-](0?[13578]|1[02]|\s\s)[\-]((1[6-9]|[2-9]\d)?\d{2}))|((0?[1-9]|[12]\d|30)[\-](0?[13456789]|1[012])[\-]((1[6-9]|[2-9]\d)?\d{2}))|((0?[1-9]|1\d|2[0-8])[\-]0?2[\-]((1[6-9]|[2-9]\d)?\d{2}))|(29[\-]0?2[\-]((1[6-9]|[2-9]\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00)))|(((0[1-9]|[12]\d|3[01])(0[13578]|1[02])((1[6-9]|[2-9]\d)?\d{2}))|((0[1-9]|[12]\d|30)(0[13456789]|1[012])((1[6-9]|[2-9]\d)?\d{2}))|((0[1-9]|1\d|2[0-8])02((1[6-9]|[2-9]\d)?\d{2}))|(2902((1[6-9]|[2-9]\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00))))$");
Could someone help me?(this expression validates even a leap year)

Here is what You asked for
System.Text.RegularExpressions.Regex rdate =
new System.Text.RegularExpressions.Regex(#"^((((0?[1-9]|[12]\d|3[01]|\s\s|\s\d)[\-](0?[13578]|1[02]|\s\s)[\-]((1[6-9]|[2-9]\d)?\d{2}|\s\s\s\s))|((0?[1-9]|[12]\d|30)[\-](0?[13456789]|1[012])[\-]((1[6-9]|[2-9]\d)?\d{2}|\s\s\s\s))|((0?[1-9]|1\d|2[0-8])[\-]0?2[\-]((1[6-9]|[2-9]\d)?\d{2}|\s\s\s\s))|(29[\-]0?2[\-]((1[6-9]|[2-9]\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00|\s\s\s\s)))|(((0[1-9]|[12]\d|3[01])(0[13578]|1[02])((1[6-9]|[2-9]\d)?\d{2}))|((0[1-9]|[12]\d|30)(0[13456789]|1[012])((1[6-9]|[2-9]\d)?\d{2}))|((0[1-9]|1\d|2[0-8])02((1[6-9]|[2-9]\d)?\d{2}))|(2902((1[6-9]|[2-9]\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00))))$");
But I am not sure it is what You really want. The regex was already patched, I continued the way. But not only it is maintenance nightmare, it behaves strange. It accepts empty day, but only when month is january, march, may... or empty. Less lines of code is not always better. I would suggest to rewrite it completely. Something simmilar to this:
protected DateTime? getDateTimeFromParts(string day, string month, string year)
{
DateTime now = DateTime.Now;
int iyear;
if (string.IsNullOrWhiteSpace(year))
{
iyear = now.Year;
}
else
{
iyear = int.Parse(year);
if (iyear >= 0 && iyear < 100) { iyear += 2000; }
}
int imonth;
if (string.IsNullOrWhiteSpace(month))
{
imonth = now.Month;
}
else
{
imonth = int.Parse(month);
}
int iday;
if (string.IsNullOrWhiteSpace(day))
{
iday = now.Day;
}
else
{
iday = int.Parse(day);
}
if (iyear <= DateTime.MaxValue.Year && iyear >= DateTime.MinValue.Year)
{
if (imonth >= 1 && imonth <= 12)
{
if (DateTime.DaysInMonth(iyear, imonth) >= iday && iday >= 1)
return new DateTime(iyear, imonth, iday);
}
}
return null;
}
protected DateTime? getDateTime(string dateStr)
{
Regex r = new Regex(#"^(\d\d)(\d\d)((\d\d)?\d\d)$");
Match m = r.Match(dateStr);
if (m.Success)
{
return getDateTimeFromParts(m.Groups[1].Value, m.Groups[2].Value, m.Groups[3].Value);
}
r = new Regex(#"^(\d?\d|\s\d|\s\s)[-](\d?\d|\s\s)[-]((\d\d)?\d\d|\s\s\s\s)$");
m = r.Match(dateStr);
if (m.Success)
{
return getDateTimeFromParts(m.Groups[1].Value, m.Groups[2].Value, m.Groups[3].Value);
}
return null;
}

Check if a datetime is in same week as other datetime

Let's say I have a list of dates in a table. Now I want to find all rows, which is in the same week as the date provided as an argument.
Let's say I have a table with:
2014-09-11
2014-09-12
2014-09-15
And I give this function the argument 2014-09-09, it has to look from monday->sunday, and realize that 09-11 and 09-12 is part of the week, but not 09-15.
How on earth to solve this?
I have thought on making a check on year, month and weeknumber, but you cannot guarantee that month is the same...
So how do you solve a problem like this?

DxCk's comment is valid. This solution will work even if the first or last week of the year cross two different years:
Check that the first day of the week for both dates fall on the same day.
Here is the code:
private bool DatesAreInTheSameWeek(DateTime date1, DateTime date2)
{
var cal = System.Globalization.DateTimeFormatInfo.CurrentInfo.Calendar;
var d1 = date1.Date.AddDays(-1 * (int)cal.GetDayOfWeek(date1));
var d2 = date2.Date.AddDays(-1 * (int)cal.GetDayOfWeek(date2));
return d1 == d2;
}

why not?
bool AreFallingInSameWeek(DateTime date1, DateTime date2)
{
return date1.AddDays(-(int)date1.DayOfWeek) == date2.AddDays(-(int)date2.DayOfWeek);
}
if you want to use any day other than Sunday as start of the week
bool AreFallingInSameWeek(DateTime date1, DateTime date2, DayOfWeek weekStartsOn)
{
return date1.AddDays(-GetOffsetedDayofWeek(date1.DayOfWeek, (int)weekStartsOn)) == date2.AddDays(-GetOffsetedDayofWeek(date2.DayOfWeek, (int)weekStartsOn));
}
int GetOffsetedDayofWeek(DayOfWeek dayOfWeek, int offsetBy)
{
return (((int)dayOfWeek - offsetBy + 7) % 7)
}

Check the DateTime.Year and Calendar.GetWeekOfYear(DateTime, ...). No need to check for the month.
EDIT: This is wrong but I can't delete it. See #Sparrow's answer below.

Use: public virtual int GetWeekOfYear(DateTime time,CalendarWeekRule rule,DayOfWeek firstDayOfWeek) of Calendar class

My requirement was to find DOBs falling on the current week. Hope this helps with your doubt. Basically the idea behind this code is as follows:
Change the DOB to current year birthday (eg; 24-02-1988 to 24-02-2018(current year).
Add a year, if the brithday week contains both dec and jan
Get the first day of today's week.
Get last day of today's week.
check if the current year birthday falls between first day and last day of today's week.
private bool DatesAreInTheSameWeek(DateTime birthday)
{
if (birthday == DateTime.MinValue)
{
return false;
}
else
{
var birtdayWithCurrentYear = new DateTime(DateTime.Today.Year, birthday.Month, birthday.Day);
if (birthday.Month == 1 && DateTime.Today.Month != 1)
{
birtdayWithCurrentYear = birtdayWithCurrentYear.AddYears(1);
}
DateTime firstDayInWeek = DateTime.Today.Date;
while (firstDayInWeek.DayOfWeek != CultureInfo.CurrentCulture.DateTimeFormat.FirstDayOfWeek)
firstDayInWeek = firstDayInWeek.AddDays(-1);var lastDayInWeek = firstDayInWeek.AddDays(7);
return birtdayWithCurrentYear < lastDayInWeek && birtdayWithCurrentYear >= firstDayInWeek;
}
}

Since the accepted answer contains error as #DxCK mentioned in comment, here is my solution for this:
public static class DateExtensions
{
private static void Swap<T>(ref T one, ref T two)
{
var temp = one;
one = two;
two = temp;
}
public static bool IsFromSameWeek(this DateTime first, DateTime second, DayOfWeek firstDayOfWeek = DayOfWeek.Monday)
{
// sort dates
if (first > second)
{
Swap(ref first, ref second);
}
var daysDiff = (second - first).TotalDays;
if (daysDiff >= 7)
{
return false;
}
const int TotalDaysInWeek = 7;
var adjustedDayOfWeekFirst = (int)first.DayOfWeek + (first.DayOfWeek < firstDayOfWeek ? TotalDaysInWeek : 0);
var adjustedDayOfWeekSecond = (int)second.DayOfWeek + (second.DayOfWeek < firstDayOfWeek ? TotalDaysInWeek : 0);
return adjustedDayOfWeekSecond >= adjustedDayOfWeekFirst;
}
}
Also here is link to another correct solution with slightly different approach.

Find start and end dates for the first date's week. Then check if the second date is between those two.
public static bool DateInsideOneWeek(DateTime date1, DateTime date2)
{
DayOfWeek firstDayOfWeek = System.Globalization.CultureInfo.CurrentCulture.DateTimeFormat.FirstDayOfWeek;
DateTime startDateOfWeek = date1.Date;
while(startDateOfWeek.DayOfWeek != firstWeekDay)
{ startDateOfWeek = startDateOfWeek.AddDays(-1d); }
DateTime endDateOfWeek = startDateOfWeek.AddDays(6d);
return date2 >= startDateOfWeek && date2 <= endDateOfWeek;
}

If you don't want to use the Calendar class you can use this function:
public static int WeekOfYear(DateTime dt)
{
int startDays = 0;
// first day of the year
DateTime firstJanuary = new DateTime(dt.Year, 1, 1);
if (firstJanuary.DayOfWeek == DayOfWeek.Tuesday)
{
startDays = 1;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Wednesday)
{
startDays = 2;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Thursday)
{
startDays = 3;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Friday)
{
startDays = 4;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Saturday)
{
startDays = 5;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Sunday)
{
startDays = 6;
}
if (DateTimeFormatInfo.CurrentInfo.FirstDayOfWeek == DayOfWeek.Sunday)
{
startDays++;
startDays = startDays % 7;
}
return ((dt.DayOfYear + startDays - 1) / 7) + 1;
}

Accepted answer doesn't work for a french calendar and when the dates are 03/10/2022 and 09/10/2022.
This worked for me :
public static partial class DateTimeExtensions
{
public static DateTime FirstDayOfWeek(this DateTime dt)
{
var culture = System.Threading.Thread.CurrentThread.CurrentCulture;
var diff = dt.DayOfWeek - culture.DateTimeFormat.FirstDayOfWeek;
if (diff < 0)
{
diff += 7;
}
return dt.AddDays(-diff).Date;
}
public static DateTime LastDayOfWeek(this DateTime dt) =>
dt.FirstDayOfWeek().AddDays(6);
public static DateTime FirstDayOfMonth(this DateTime dt) =>
new DateTime(dt.Year, dt.Month, 1);
public static DateTime LastDayOfMonth(this DateTime dt) =>
dt.FirstDayOfMonth().AddMonths(1).AddDays(-1);
public static DateTime FirstDayOfNextMonth(this DateTime dt) =>
dt.FirstDayOfMonth().AddMonths(1);
public static int GetWeeekNumber(this DateTime dt)
{
CultureInfo culture = System.Threading.Thread.CurrentThread.CurrentCulture;
Calendar myCal = culture.Calendar;
// Gets the DTFI properties required by GetWeekOfYear.
CalendarWeekRule myCWR = culture.DateTimeFormat.CalendarWeekRule;
DayOfWeek myFirstDOW = culture.DateTimeFormat.FirstDayOfWeek;
return myCal.GetWeekOfYear(dt, myCWR, myFirstDOW);
}
public static bool IsInTheSameWeek(this DateTime date1, DateTime date2)
{
return date1.GetWeeekNumber() == date2.GetWeeekNumber();
}
}
Usage :
item.Week.IsInTheSameWeek(Week)

when Date of Birth under 1 year shows 0 Years old I want to convert it to months and days

In my project I am working on patient flow where if the patient only a couple days old then my UI is just showing 0 year old instead of, for example 2 days old or 6 months old.
I want to include this logic to calculate age in months and days of patient.
below is the C# function i am using for calculating age of patient:
public int CalculatedAge
{
get
{
if (Patient.DateOfBirth == null && !Patient.Age.HasValue)
return 0;
else if (Patient.DateOfBirth == null && Patient.Age != null && Patient.Age.HasValue)
return Patient.Age.Value;
else if (Patient.DateOfBirth != null)
return DateTime.Now.ToUniversalTime().Year - Patient.DateOfBirth.Value.Year;
return 0;
}
}

You can create new entities.
enum AgeUnits
{
Days,
Months,
Years
}
class Age
{
public int Value { get; private set; }
public AgeUnits Units { get; private set; }
public Age(int value, AgeUnits ageUnits)
{
Value = value;
Units = ageUnits;
}
}
Then you can use Age as type of CalculatedAge property.
public Age CalculatedAge
{
get
{
if (Patient.DateOfBirth.HasValue)
{
DateTime bday = Patient.DateOfBirth.Value;
DateTime now = DateTime.UtcNow;
if (bday.AddYears(1) < now)
{
int years = now.Year - bday.year;
if (bday > now.AddYears(-years))
years--;
return new Age(years, AgeUnits.Years);
}
else if (bday.AddMonths(1) < now)
{
int months = (now.Months - bday.Months + 12) % 12;
if (bday > now.AddMonths(-months))
months--;
return new Age(months, AgeUnits.Months);
}
else
{
int days = (now - bday).Days;
return new Age(days, AgeUnits.Days);
}
}
else
{
if (Patient.Age.HasValue)
return new Age(Patient.Age.Value, AgeUnits.Years);
else
return null;
}
}
}

public Age CalculatedAge
{
get
{
if (Patient.DateOfBirth == null && Patient.Age != null && Patient.Age.HasValue)
return new Age(Patient.Age.Value);
else if (Patient.DateOfBirth != null)
{
DateTime now = DateTime.UtcNow;
TimeSpan tsAge = now - Patient.DateOfBirth;
DateTime age = new DateTime(tsAge.Ticks);
return new Age(age.Year - 1, age.Month - 1, age.Day - 1);
}
return new Age(0);
}
}
And this is the Age struct:
struct Age
{
public int Years, Months, Days; //It's a small struct, properties aren't necessary
public Age(int years, int months = 0, int days = 0) { this.Years = years; this.Months = months; this.Days = days; }
}
Obviously you can just check the values in with IF statements but a struct for this purpose is cleaner in my opinion.
return new Age(age.Year - 1, age.Month - 1, age.Day - 1); This part is due to the fact that the MinValue of a DateTime object is 01/01/0001 so you need to substract that to get the real age.