Today I was given the task of finding the age of a person, provided the birth date. When I was given the task, I just said, just use the DateDiff function. But it is not that simple.

One thing I wanted was to keep the code simple and in a few lines of code. Here goes my first iteration.

static void CalculateAge() { DateTime dateOfBirth; DateTime.TryParse("02/18/2008", out dateOfBirth); DateTime currentDate = DateTime.Now; TimeSpan difference = currentDate.Subtract(dateOfBirth); // This is to convert the timespan to datetime object DateTime age = DateTime.MinValue + difference; // Min value is 01/01/0001 // Actual age is say 24 yrs, 9 months and 3 days represented as timespan // Min Valye + actual age = 25 yrs , 10 months and 4 days. // subtract our addition or 1 on all components to get the actual date. int ageInYears = age.Year - 1; int ageInMonths = age.Month - 1; int ageInDays = age.Day - 1; Console.WriteLine("{0}, {1}, {2}", ageInYears, ageInMonths, ageInDays); }

But then, there were problems with this method. If the current date is ’06/18/2009′ and the birth date was ’04/18/2000′, it returns, 9 yrs, 2 months and 2 days. The 2 days part is wrong. I didn’t have any clue as to why it appears.

Then I went down to the basics, using elementary mathematics of subtraction. Here goes the second iteration of the code.

static void CalculateAge2() { DateTime dateOfBirth = new DateTime(2000, 6, 18); int ageInYears = 0; int ageInMonths = 0; int ageInDays = 0; CalculateAge(dateOfBirth, out ageInYears, out ageInMonths, out ageInDays); Console.WriteLine("{0}, {1}, {2}", ageInYears, ageInMonths, ageInDays); } /// /// Calculate the Age of a person given the birthdate. /// static void CalculateAge(DateTime adtDateOfBirth, out int aintNoOfYears, out int aintNoOfMonths, out int aintNoOfDays) { // get current date. DateTime adtCurrentDate = DateTime.Now; // find the literal difference aintNoOfDays = adtCurrentDate.Day - adtDateOfBirth.Day; aintNoOfMonths = adtCurrentDate.Month - adtDateOfBirth.Month; aintNoOfYears = adtCurrentDate.Year - adtDateOfBirth.Year; if (aintNoOfDays < 0) { aintNoOfDays += DateTime.DaysInMonth(adtCurrentDate.Year, adtCurrentDate.Month); aintNoOfMonths--; } if (aintNoOfMonths < 0) { aintNoOfMonths += 12; aintNoOfYears--; } }

And it works like a charm for all scenarios I throw upon it.

Scenario 1:

Current Date : 15 – 09 – 2009

Birth Date : 09 – 03 – 2000

Just a difference gives the result

Age : 6 – 6 – 9 Result is 9 yrs, 6 months, 6 days.

Scenario 2:

Current Date : 15 – 09 – 2009

Birth Date : 28 – 07 – 2000

Here since 15 – 28 < 0: we borrow one from the month and then add the no of days in the month to the current date. 15 + 30 = 45: 45 – 28 = 17 days

Then since one month is borrowed: 08 – 07 = 01 months

Remaining is normal difference

Age : 17 – 1 – 9 Result is 9 yrs, 1 months, 17 days.

Scenario 3:

Current Date : 15 – 09 – 2009

Birth Date : 28 – 12 – 2000

Here since 15 – 28 < 0: we borrow one from the month and then add the no of days in the current month to the current date. 15 + 30 = 45: 45 – 28 = 17 days

Then since one month is borrowed: 08 – 12: So we are supposed to borrow a year and add no of months in current year to current month. 08 + 12 = 20: 20 – 12 = 8 months

Since a year was borrowed: 2008 – 2000: 8 yrs

Remaining is normal difference

Age : 17 – 8 – 8 Result is 8 yrs, 8 months, 17 days.

But I know there must be better ways to do it. Feel free to drop in code snippets. Comments too are most welcome.

You got extra 2 days since you did not take leap years into account.

Nice job! Keep rocking 🙂

This was the most helpful post I surfed for, most neat and clear. Thanks.

Thank you.

Good job. Thank you

thanx for the help………

The condition of the two if loops of CalculateAge method displays <

What should be the check there?

Ignore my previous reply. The second logic is awesome. Thank you.

A scenario that would fail here is:

Current Date : 11 – 04 – 2011

Birth Date : 28 – 03 – 2011

The logic is calculating the age as 13 days instead of 14. How can we correct this?

I think the 29th line should be

aintNoOfDays += DateTime.DaysInMonth(adtDateOfBirth.Year, adtDateOfBirth.Month);

plz help me guyz .. the if statement in line 27 & 33 shows errors in C# .. I dont understand why ?? plz I have an exam 2morrow

This is awesome, thank you 🙂

i have a better logic…but a bit longer…but accurate..

Please do post it in the reply, so someone looking for better solution can use it.