MSDN example [modified] (oops, my bad!)

leppie

public static int GetAge(string birthDate)
{
DateTime birth;

try
{
birth = DateTime.Parse(birthDate);
}
catch (Exception ex)
{
throw new ApplicationException("Unable to read birth date.", ex);
}

if (DateTime.Today.Month < birth.Month) //it is before your birthday
{
return DateTime.Today.Year - birth.Year - 1;
}
else if (DateTime.Today.Month > birth.Month) //it is after your birthday
{
return DateTime.Today.Year - birth.Year;
}
else // DateTime.Today.Month == birth.Month //we don't know yet
{
if (DateTime.Today.Day < birth.Day) //it is before your birthday
{
return DateTime.Today.Year - birth.Year - 1;
}
else //it is your birthday, or it is after your birthday
{
return DateTime.Today.Year - birth.Year;
}
}
}

:sigh: :doh: To be seen @ http://msdn.microsoft.com/en-us/library/bb126477.aspx[^] UPDATE: I was under the impression, Timespan had a TotalYears property. But now, looking at the logic, I can see why it does not have one. :-O

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 2 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))

modified on Wednesday, April 15, 2009 10:40 AM

OriginalGriff · modified on Wednesday, April 15, 2009 10:40 AM

Yes. Ok. This is a bit easier on the eye...

    public static int GetAge(string birthDate)
        {
        DateTime birth;
        try
            {
            birth = DateTime.Parse(birthDate);
            }
        catch (Exception ex)
            {
            throw new ApplicationException("Unable to read birth date.", ex);
            }
        DateTime now = DateTime.Today;
        if (now.DayOfYear < birth.DayOfYear)
            {
            // Before your birthday
            return now.Year - birth.Year - 1;
            }
        return now.Year - birth.Year;
        }

Oh, and it works around midnight, too...

leppie

Oh dear! Another one bites the dust! :sigh: bad hint: TimeSpan UPDATE: Sorry :)

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 2 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))

modified on Wednesday, April 15, 2009 10:58 AM

0x3c0

Why not just use something like this?

public static int GetAge(string birthDate)
{
DateTime birth;
TimeSpan livingAge; /* This will be inaccurate by the time it's
* been calculated but I don't think the user
* will care about a few ticks */

if(!DateTime.Parse(birthDate, out birth))
    throw new InvalidCastException("Unable to parse birth date");
livingAge = DateTime.Now - birth;
return (livingAge + DateTime.MinValue).Years - 1;

}

Luc 648011

Huh? either you want an exception, so you use Parse; or you don't want one and use TryParse. :)

Luc 648011 · modified on Wednesday, April 15, 2009 10:58 AM

Part of the ugly code is due to the fact that TimeSpan does not have Months or Years properties; [EDITED] while it's MaxValue corresponds to more than 10 million days, without knowing the reference it can't decide on how many days fit in a month, and how leap years need handled. [/EDITED] :)

modified on Wednesday, April 15, 2009 9:52 AM

Ian Shlasko · modified on Wednesday, April 15, 2009 10:40 AM

It needs to be done in true OOP style...

public static int GetAge(string birthDate)
{
DateTimeParser dtpc = new DateTimeParser() { DateAsString = birthDate };
DateTimeWithoutYearComparer dtwyc = new DateTimeWithoutYearComparer();

return dtwyc.PerformComparisonAndReturnDifferenceInYears(DateTime.Today, dtpc.Parse());
}

public class DateTimeParser
{
public string DateAsString { get; set; }
public DateTime Parse()
{
throw new NotImplementedException("We're too lazy to actually write code");
}
}

public class DateTimeWithoutYearComparer
{
public DateTimeWithoutYearComparer()
{
InitializeComponent();
}

private void InitializeComponent()
{
// Here there be dragons
}

public int PerformComparisonAndReturnDifferenceInYears(DateTime a, DateTime b)
{
/* The team would like to congratulate Bill Lumbergh for winning
* the "Think of the Longest and Dumbest Name for a Function" contest.
*/
return 42;
}
}

Sorry, I was reading that thread in the Lounge about funny code comments, and, well, my mind is pretty warped to begin with... The scary thing is that if I typed this into Visual Studio instead of here, I think it might actually compile (and crash).

0x3c0

It's just my rather broken coding style. I never learned one formally. If you wanted, you could replace the throw statement with return -1

Yusuf · modified on Wednesday, April 15, 2009 10:40 AM

where do you think, the horror codes, plz send codz now, my code no work... stem from?

Yusuf Oh didn't you notice, analogous to square roots, they recently introduced rectangular, circular, and diamond roots to determine the size of the corresponding shapes when given the area. Luc Pattyn[^]

leppie · modified on Wednesday, April 15, 2009 9:52 AM

Arggh, I could swear TimeSpan had those properties! Now I feel like the fool! :-O

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 2 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))

leppie

Cool, not what I had in mind, but definitely better than what I had in mind! :)

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 2 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))

0x3c0

Thanks. For what its worth, what did you have in mind?

leppie

Computafreak wrote:

For what its worth, what did you have in mind?

For some reason I thought Timespan had a TotalYears property... :doh:

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 2 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))

Luc 648011

yet incorrect, since it assumes months and leap years evolve from day of birth in the same way as they do from DateTime.MinValue The net result is that close to one's birthday the formula can be off by 1. This one is much safer, although still not perfect: DateTime.Today.Subtract(DateTime.Parse(birthday)).Days/365.242374 The perfect solution really uses ToDay.Years-DateTime.Parse(birthday).Years and adjusts by one according to the result of ToDay.DayOfYear < DateTime.Parse(birthday).DayOfYear :)

leppie

Actually, after carefully looking at your solution, it appears to be wrong.

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 2 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))

leppie

Ahh yes, I just noticed that 2 minutes ago :)

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 2 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))

0x3c0

Ah, well. Live and learn

leppie

Good answer in fact :)

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 2 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))

Lutoslaw · modified on Wednesday, April 15, 2009 10:40 AM

public static int GetAge(string birthDate)
{
throw new CoderIsABoorException();
}

Greetings - Gajatko Portable.NET is part of DotGNU, a project to build a complete Free Software replacement for .NET - a system that truly belongs to the developers.

supercat9

For that approach to work, wouldn't you have to add 306 days to both the birthdate and the present time before using the Year and DayOfYear properties? The notion that someone born on 2/28/2000 would have had to wait 366 days to be "one year old", while someone born on 3/1/2000 would only have to wait 365 days, is somewhat artificial but it is certainly well-established. #2/28/2000#.DayOfYear == 59 #2/28/2001#.DayOfYear == 59 #3/1/2000#.DayOfYear == 61 #3/1/2001#.DayOfYear == 60 #2/28/2000#.AddDays(306).DayOfYear == 365 #2/28/2001#.AddDays(306).DayOfYear == 365 #3/1/2000#.AddDays(306).DayOfYear == 1 #3/1/2001#.AddDays(306).DayOfYear == 1 Of course, adding 306 days has an ugliness all its own. My own preference would probably be to simply format the thing as MMDDHHMMSS, do a string compare, and adjust the year appropriately, but another option would be to format as YYYYMMDDHHMMSS, convert to a long or double, subtract, and divide by 10,000,000,000.