C#: Calculate Age in Years, Month and Days

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.

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12 thoughts on “C#: Calculate Age in Years, Month and Days

  1. 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);

  2. 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

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