Answer by EgoPingvina for Difference in months between two dates

Someone must have done it))

The extension method returns the number of full months between the given dates. No matter in what order the dates are received, a natural number will always be returned.No approximate calculations as in the "correct" answer.

    /// <summary>    /// Returns the difference between dates in months.    /// </summary>    /// <param name="current">First considered date.</param>    /// <param name="another">Second considered date.</param>    /// <returns>The number of full months between the given dates.</returns>    public static int DifferenceInMonths(this DateTime current, DateTime another)    {        DateTime previous, next;        if (current > another)        {            previous = another;            next     = current;        }        else        {            previous = current;            next     = another;        }        return            (next.Year - previous.Year) * 12     // multiply the difference in years by 12 months+ next.Month - previous.Month          // add difference in months+ (previous.Day <= next.Day ? 0 : -1); // if the day of the next date has not reached the day of the previous one, then the last month has not yet ended    }

But if you still want to get the fractional parts of the months, you just need to add one more term to the return:

+ (next.Day - previous.Day) / DateTime.DaysInMonth(previous.Year, previous.Month)